make git barf when an alias changes environment variables
[gitweb.git] / config.c
index 18d59ee6e3295d66c091e32a0cef15327c94c36a..0614c2b29fa93b66065ec6bc20712d38193aec89 100644 (file)
--- a/config.c
+++ b/config.c
@@ -6,12 +6,14 @@
  *
  */
 #include "cache.h"
-#include <regex.h>
 
 #define MAXNAME (256)
 
 static FILE *config_file;
+static const char *config_file_name;
 static int config_linenr;
+static int zlib_compression_seen;
+
 static int get_next_char(void)
 {
        int c;
@@ -59,6 +61,12 @@ static char *parse_value(void)
                        space = 1;
                        continue;
                }
+               if (!quote) {
+                       if (c == ';' || c == '#') {
+                               comment = 1;
+                               continue;
+                       }
+               }
                if (space) {
                        if (len)
                                value[len++] = ' ';
@@ -92,16 +100,15 @@ static char *parse_value(void)
                        quote = 1-quote;
                        continue;
                }
-               if (!quote) {
-                       if (c == ';' || c == '#') {
-                               comment = 1;
-                               continue;
-                       }
-               }
                value[len++] = c;
        }
 }
 
+static inline int iskeychar(int c)
+{
+       return isalnum(c) || c == '-';
+}
+
 static int get_value(config_fn_t fn, char *name, unsigned int len)
 {
        int c;
@@ -112,7 +119,7 @@ static int get_value(config_fn_t fn, char *name, unsigned int len)
                c = get_next_char();
                if (c == EOF)
                        break;
-               if (!isalnum(c))
+               if (!iskeychar(c))
                        break;
                name[len++] = tolower(c);
                if (len >= MAXNAME)
@@ -133,6 +140,41 @@ static int get_value(config_fn_t fn, char *name, unsigned int len)
        return fn(name, value);
 }
 
+static int get_extended_base_var(char *name, int baselen, int c)
+{
+       do {
+               if (c == '\n')
+                       return -1;
+               c = get_next_char();
+       } while (isspace(c));
+
+       /* We require the format to be '[base "extension"]' */
+       if (c != '"')
+               return -1;
+       name[baselen++] = '.';
+
+       for (;;) {
+               int c = get_next_char();
+               if (c == '\n')
+                       return -1;
+               if (c == '"')
+                       break;
+               if (c == '\\') {
+                       c = get_next_char();
+                       if (c == '\n')
+                               return -1;
+               }
+               name[baselen++] = c;
+               if (baselen > MAXNAME / 2)
+                       return -1;
+       }
+
+       /* Final ']' */
+       if (get_next_char() != ']')
+               return -1;
+       return baselen;
+}
+
 static int get_base_var(char *name)
 {
        int baselen = 0;
@@ -143,7 +185,9 @@ static int get_base_var(char *name)
                        return -1;
                if (c == ']')
                        return baselen;
-               if (!isalnum(c) && c != '.')
+               if (isspace(c))
+                       return get_extended_base_var(name, baselen, c);
+               if (!iskeychar(c) && c != '.')
                        return -1;
                if (baselen > MAXNAME / 2)
                        return -1;
@@ -186,7 +230,7 @@ static int git_parse_file(config_fn_t fn)
                if (get_value(fn, var, baselen+1) < 0)
                        break;
        }
-       die("bad config file line %d", config_linenr);
+       die("bad config file line %d in %s", config_linenr, config_file_name);
 }
 
 int git_config_int(const char *name, const char *value)
@@ -196,8 +240,14 @@ int git_config_int(const char *name, const char *value)
                int val = strtol(value, &end, 0);
                if (!*end)
                        return val;
+               if (!strcasecmp(end, "k"))
+                       return val * 1024;
+               if (!strcasecmp(end, "m"))
+                       return val * 1024 * 1024;
+               if (!strcasecmp(end, "g"))
+                       return val * 1024 * 1024 * 1024;
        }
-       die("bad config value for '%s'", name);
+       die("bad config value for '%s' in %s", name, config_file_name);
 }
 
 int git_config_bool(const char *name, const char *value)
@@ -206,9 +256,9 @@ int git_config_bool(const char *name, const char *value)
                return 1;
        if (!*value)
                return 0;
-       if (!strcasecmp(value, "true"))
+       if (!strcasecmp(value, "true") || !strcasecmp(value, "yes"))
                return 1;
-       if (!strcasecmp(value, "false"))
+       if (!strcasecmp(value, "false") || !strcasecmp(value, "no"))
                return 0;
        return git_config_int(name, value) != 0;
 }
@@ -221,37 +271,167 @@ int git_default_config(const char *var, const char *value)
                return 0;
        }
 
-       if (!strcmp(var, "core.symrefsonly")) {
-               only_use_symrefs = git_config_bool(var, value);
+       if (!strcmp(var, "core.symlinks")) {
+               has_symlinks = git_config_bool(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.bare")) {
+               is_bare_repository_cfg = git_config_bool(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.ignorestat")) {
+               assume_unchanged = git_config_bool(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.prefersymlinkrefs")) {
+               prefer_symlink_refs = git_config_bool(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.logallrefupdates")) {
+               log_all_ref_updates = git_config_bool(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.warnambiguousrefs")) {
+               warn_ambiguous_refs = git_config_bool(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.loosecompression")) {
+               int level = git_config_int(var, value);
+               if (level == -1)
+                       level = Z_DEFAULT_COMPRESSION;
+               else if (level < 0 || level > Z_BEST_COMPRESSION)
+                       die("bad zlib compression level %d", level);
+               zlib_compression_level = level;
+               zlib_compression_seen = 1;
+               return 0;
+       }
+
+       if (!strcmp(var, "core.compression")) {
+               int level = git_config_int(var, value);
+               if (level == -1)
+                       level = Z_DEFAULT_COMPRESSION;
+               else if (level < 0 || level > Z_BEST_COMPRESSION)
+                       die("bad zlib compression level %d", level);
+               core_compression_level = level;
+               core_compression_seen = 1;
+               if (!zlib_compression_seen)
+                       zlib_compression_level = level;
+               return 0;
+       }
+
+       if (!strcmp(var, "core.packedgitwindowsize")) {
+               int pgsz_x2 = getpagesize() * 2;
+               packed_git_window_size = git_config_int(var, value);
+
+               /* This value must be multiple of (pagesize * 2) */
+               packed_git_window_size /= pgsz_x2;
+               if (packed_git_window_size < 1)
+                       packed_git_window_size = 1;
+               packed_git_window_size *= pgsz_x2;
+               return 0;
+       }
+
+       if (!strcmp(var, "core.packedgitlimit")) {
+               packed_git_limit = git_config_int(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.deltabasecachelimit")) {
+               delta_base_cache_limit = git_config_int(var, value);
+               return 0;
+       }
+
+       if (!strcmp(var, "core.autocrlf")) {
+               if (value && !strcasecmp(value, "input")) {
+                       auto_crlf = -1;
+                       return 0;
+               }
+               auto_crlf = git_config_bool(var, value);
                return 0;
        }
 
        if (!strcmp(var, "user.name")) {
-               strncpy(git_default_name, value, sizeof(git_default_name));
+               strlcpy(git_default_name, value, sizeof(git_default_name));
                return 0;
        }
 
        if (!strcmp(var, "user.email")) {
-               strncpy(git_default_email, value, sizeof(git_default_email));
+               strlcpy(git_default_email, value, sizeof(git_default_email));
                return 0;
        }
 
-       /* Add other config variables here.. */
+       if (!strcmp(var, "i18n.commitencoding")) {
+               git_commit_encoding = xstrdup(value);
+               return 0;
+       }
+
+       if (!strcmp(var, "i18n.logoutputencoding")) {
+               git_log_output_encoding = xstrdup(value);
+               return 0;
+       }
+
+
+       if (!strcmp(var, "pager.color") || !strcmp(var, "color.pager")) {
+               pager_use_color = git_config_bool(var,value);
+               return 0;
+       }
+
+       /* Add other config variables here and to Documentation/config.txt. */
        return 0;
 }
 
-int git_config(config_fn_t fn)
+int git_config_from_file(config_fn_t fn, const char *filename)
 {
        int ret;
-       FILE *f = fopen(git_path("config"), "r");
+       FILE *f = fopen(filename, "r");
 
        ret = -1;
        if (f) {
                config_file = f;
+               config_file_name = filename;
                config_linenr = 1;
                ret = git_parse_file(fn);
                fclose(f);
+               config_file_name = NULL;
+       }
+       return ret;
+}
+
+int git_config(config_fn_t fn)
+{
+       int ret = 0;
+       char *repo_config = NULL;
+       const char *home = NULL, *filename;
+
+       /* $GIT_CONFIG makes git read _only_ the given config file,
+        * $GIT_CONFIG_LOCAL will make it process it in addition to the
+        * global config file, the same way it would the per-repository
+        * config file otherwise. */
+       filename = getenv(CONFIG_ENVIRONMENT);
+       if (!filename) {
+               if (!access(ETC_GITCONFIG, R_OK))
+                       ret += git_config_from_file(fn, ETC_GITCONFIG);
+               home = getenv("HOME");
+               filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
+               if (!filename)
+                       filename = repo_config = xstrdup(git_path("config"));
        }
+
+       if (home) {
+               char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
+               if (!access(user_config, R_OK))
+                       ret = git_config_from_file(fn, user_config);
+               free(user_config);
+       }
+
+       ret += git_config_from_file(fn, filename);
+       free(repo_config);
        return ret;
 }
 
@@ -267,7 +447,7 @@ static struct {
        int do_not_match;
        regex_t* value_regex;
        int multi_replace;
-       off_t offset[MAX_MATCHES];
+       size_t offset[MAX_MATCHES];
        enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
        int seen;
 } store;
@@ -282,6 +462,9 @@ static int matches(const char* key, const char* value)
 
 static int store_aux(const char* key, const char* value)
 {
+       const char *ep;
+       size_t section_len;
+
        switch (store.state) {
        case KEY_SEEN:
                if (matches(key, value)) {
@@ -299,12 +482,29 @@ static int store_aux(const char* key, const char* value)
                }
                break;
        case SECTION_SEEN:
-               if (strncmp(key, store.key, store.baselen+1)) {
+               /*
+                * What we are looking for is in store.key (both
+                * section and var), and its section part is baselen
+                * long.  We found key (again, both section and var).
+                * We would want to know if this key is in the same
+                * section as what we are looking for.  We already
+                * know we are in the same section as what should
+                * hold store.key.
+                */
+               ep = strrchr(key, '.');
+               section_len = ep - key;
+
+               if ((section_len != store.baselen) ||
+                   memcmp(key, store.key, section_len+1)) {
                        store.state = SECTION_END_SEEN;
                        break;
-               } else
-                       /* do not increment matches: this is no match */
-                       store.offset[store.seen] = ftell(config_file);
+               }
+
+               /*
+                * Do not increment matches: this is no match, but we
+                * just made sure we are in the desired section.
+                */
+               store.offset[store.seen] = ftell(config_file);
                /* fallthru */
        case SECTION_END_SEEN:
        case START:
@@ -312,42 +512,114 @@ static int store_aux(const char* key, const char* value)
                        store.offset[store.seen] = ftell(config_file);
                        store.state = KEY_SEEN;
                        store.seen++;
-               } else if(!strncmp(key, store.key, store.baselen))
-                       store.state = SECTION_SEEN;
+               } else {
+                       if (strrchr(key, '.') - key == store.baselen &&
+                             !strncmp(key, store.key, store.baselen)) {
+                                       store.state = SECTION_SEEN;
+                                       store.offset[store.seen] = ftell(config_file);
+                       }
+               }
        }
        return 0;
 }
 
-static void store_write_section(int fd, const char* key)
+static int write_error()
 {
-       write(fd, "[", 1);
-       write(fd, key, store.baselen);
-       write(fd, "]\n", 2);
+       fprintf(stderr, "Failed to write new configuration file\n");
+
+       /* Same error code as "failed to rename". */
+       return 4;
+}
+
+static int store_write_section(int fd, const char* key)
+{
+       const char *dot = strchr(key, '.');
+       int len1 = store.baselen, len2 = -1;
+
+       dot = strchr(key, '.');
+       if (dot) {
+               int dotlen = dot - key;
+               if (dotlen < len1) {
+                       len2 = len1 - dotlen - 1;
+                       len1 = dotlen;
+               }
+       }
+
+       if (write_in_full(fd, "[", 1) != 1 ||
+           write_in_full(fd, key, len1) != len1)
+               return 0;
+       if (len2 >= 0) {
+               if (write_in_full(fd, " \"", 2) != 2)
+                       return 0;
+               while (--len2 >= 0) {
+                       unsigned char c = *++dot;
+                       if (c == '"')
+                               if (write_in_full(fd, "\\", 1) != 1)
+                                       return 0;
+                       if (write_in_full(fd, &c, 1) != 1)
+                               return 0;
+               }
+               if (write_in_full(fd, "\"", 1) != 1)
+                       return 0;
+       }
+       if (write_in_full(fd, "]\n", 2) != 2)
+               return 0;
+
+       return 1;
 }
 
-static void store_write_pair(int fd, const char* key, const char* value)
+static int store_write_pair(int fd, const char* key, const char* value)
 {
        int i;
+       int length = strlen(key+store.baselen+1);
+       int quote = 0;
 
-       write(fd, "\t", 1);
-       write(fd, key+store.baselen+1,
-               strlen(key+store.baselen+1));
-       write(fd, " = ", 3);
+       /* Check to see if the value needs to be quoted. */
+       if (value[0] == ' ')
+               quote = 1;
+       for (i = 0; value[i]; i++)
+               if (value[i] == ';' || value[i] == '#')
+                       quote = 1;
+       if (value[i-1] == ' ')
+               quote = 1;
+
+       if (write_in_full(fd, "\t", 1) != 1 ||
+           write_in_full(fd, key+store.baselen+1, length) != length ||
+           write_in_full(fd, " = ", 3) != 3)
+               return 0;
+       if (quote && write_in_full(fd, "\"", 1) != 1)
+               return 0;
        for (i = 0; value[i]; i++)
                switch (value[i]) {
-               case '\n': write(fd, "\\n", 2); break;
-               case '\t': write(fd, "\\t", 2); break;
-               case '"': case '\\': write(fd, "\\", 1);
-               default: write(fd, value+i, 1);
-       }
-       write(fd, "\n", 1);
+               case '\n':
+                       if (write_in_full(fd, "\\n", 2) != 2)
+                               return 0;
+                       break;
+               case '\t':
+                       if (write_in_full(fd, "\\t", 2) != 2)
+                               return 0;
+                       break;
+               case '"':
+               case '\\':
+                       if (write_in_full(fd, "\\", 1) != 1)
+                               return 0;
+               default:
+                       if (write_in_full(fd, value+i, 1) != 1)
+                               return 0;
+                       break;
+               }
+       if (quote && write_in_full(fd, "\"", 1) != 1)
+               return 0;
+       if (write_in_full(fd, "\n", 1) != 1)
+               return 0;
+       return 1;
 }
 
-static int find_beginning_of_line(const char* contents, int size,
-       int offset_, int* found_bracket)
+static ssize_t find_beginning_of_line(const char* contents, size_t size,
+       size_t offset_, int* found_bracket)
 {
-       int equal_offset = size, bracket_offset = size;
-       int offset;
+       size_t equal_offset = size, bracket_offset = size;
+       ssize_t offset;
 
        for (offset = offset_-2; offset > 0 
                        && contents[offset] != '\n'; offset--)
@@ -395,21 +667,31 @@ int git_config_set(const char* key, const char* value)
 int git_config_set_multivar(const char* key, const char* value,
        const char* value_regex, int multi_replace)
 {
-       int i;
-       struct stat st;
-       int fd;
-       char* config_file = strdup(git_path("config"));
-       char* lock_file = strdup(git_path("config.lock"));
+       int i, dot;
+       int fd = -1, in_fd;
+       int ret;
+       char* config_filename;
+       char* lock_file;
        const char* last_dot = strrchr(key, '.');
 
+       config_filename = getenv(CONFIG_ENVIRONMENT);
+       if (!config_filename) {
+               config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
+               if (!config_filename)
+                       config_filename  = git_path("config");
+       }
+       config_filename = xstrdup(config_filename);
+       lock_file = xstrdup(mkpath("%s.lock", config_filename));
+
        /*
         * Since "key" actually contains the section name and the real
         * key name separated by a dot, we have to know where the dot is.
         */
 
-       if (last_dot == NULL) { 
+       if (last_dot == NULL) {
                fprintf(stderr, "key does not contain a section: %s\n", key);
-               return 2;
+               ret = 2;
+               goto out_free;
        }
        store.baselen = last_dot - key;
 
@@ -418,16 +700,29 @@ int git_config_set_multivar(const char* key, const char* value,
        /*
         * Validate the key and while at it, lower case it for matching.
         */
-       store.key = (char*)malloc(strlen(key)+1);
-       for (i = 0; key[i]; i++)
-               if (i != store.baselen &&
-                               ((!isalnum(key[i]) && key[i] != '.') ||
-                                (i == store.baselen+1 && !isalpha(key[i])))) {
-                       fprintf(stderr, "invalid key: %s\n", key);
+       store.key = xmalloc(strlen(key) + 1);
+       dot = 0;
+       for (i = 0; key[i]; i++) {
+               unsigned char c = key[i];
+               if (c == '.')
+                       dot = 1;
+               /* Leave the extended basename untouched.. */
+               if (!dot || i > store.baselen) {
+                       if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
+                               fprintf(stderr, "invalid key: %s\n", key);
+                               free(store.key);
+                               ret = 1;
+                               goto out_free;
+                       }
+                       c = tolower(c);
+               } else if (c == '\n') {
+                       fprintf(stderr, "invalid key (newline): %s\n", key);
                        free(store.key);
-                       return 1;
-               } else
-                       store.key[i] = tolower(key[i]);
+                       ret = 1;
+                       goto out_free;
+               }
+               store.key[i] = c;
+       }
        store.key[i] = 0;
 
        /*
@@ -435,40 +730,41 @@ int git_config_set_multivar(const char* key, const char* value,
         * contents of .git/config will be written into it.
         */
        fd = open(lock_file, O_WRONLY | O_CREAT | O_EXCL, 0666);
-       if (fd < 0) {
+       if (fd < 0 || adjust_shared_perm(lock_file)) {
                fprintf(stderr, "could not lock config file\n");
                free(store.key);
-               return -1;
+               ret = -1;
+               goto out_free;
        }
 
        /*
         * If .git/config does not exist yet, write a minimal version.
         */
-       if (stat(config_file, &st)) {
-               static const char contents[] =
-                       "#\n"
-                       "# This is the config file\n"
-                       "#\n"
-                       "\n";
-
+       in_fd = open(config_filename, O_RDONLY);
+       if ( in_fd < 0 ) {
                free(store.key);
 
+               if ( ENOENT != errno ) {
+                       error("opening %s: %s", config_filename,
+                             strerror(errno));
+                       ret = 3; /* same as "invalid config file" */
+                       goto out_free;
+               }
                /* if nothing to unset, error out */
                if (value == NULL) {
-                       close(fd);
-                       unlink(lock_file);
-                       return 5;
+                       ret = 5;
+                       goto out_free;
                }
 
                store.key = (char*)key;
-
-               write(fd, contents, sizeof(contents)-1);
-               store_write_section(fd, key);
-               store_write_pair(fd, key, value);
-       } else{
-               int in_fd;
+               if (!store_write_section(fd, key) ||
+                   !store_write_pair(fd, key, value))
+                       goto write_err_out;
+       } else {
+               struct stat st;
                char* contents;
-               int i, copy_begin, copy_end, new_line = 0;
+               size_t contents_sz, copy_begin, copy_end;
+               int i, new_line = 0;
 
                if (value_regex == NULL)
                        store.value_regex = NULL;
@@ -479,13 +775,14 @@ int git_config_set_multivar(const char* key, const char* value,
                        } else
                                store.do_not_match = 0;
 
-                       store.value_regex = (regex_t*)malloc(sizeof(regex_t));
+                       store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
                        if (regcomp(store.value_regex, value_regex,
                                        REG_EXTENDED)) {
-                               fprintf(stderr, "Invalid pattern: %s",
+                               fprintf(stderr, "Invalid pattern: %s\n",
                                        value_regex);
                                free(store.value_regex);
-                               return 6;
+                               ret = 6;
+                               goto out_free;
                        }
                }
 
@@ -499,14 +796,15 @@ int git_config_set_multivar(const char* key, const char* value,
                 * As a side effect, we make sure to transform only a valid
                 * existing config file.
                 */
-               if (git_config(store_aux)) {
+               if (git_config_from_file(store_aux, config_filename)) {
                        fprintf(stderr, "invalid config file\n");
                        free(store.key);
                        if (store.value_regex != NULL) {
                                regfree(store.value_regex);
                                free(store.value_regex);
                        }
-                       return 3;
+                       ret = 3;
+                       goto out_free;
                }
 
                free(store.key);
@@ -518,13 +816,13 @@ int git_config_set_multivar(const char* key, const char* value,
                /* if nothing to unset, or too many matches, error out */
                if ((store.seen == 0 && value == NULL) ||
                                (store.seen > 1 && multi_replace == 0)) {
-                       close(fd);
-                       unlink(lock_file);
-                       return 5;
+                       ret = 5;
+                       goto out_free;
                }
 
-               in_fd = open(config_file, O_RDONLY, 0666);
-               contents = mmap(NULL, st.st_size, PROT_READ,
+               fstat(in_fd, &st);
+               contents_sz = xsize_t(st.st_size);
+               contents = xmmap(NULL, contents_sz, PROT_READ,
                        MAP_PRIVATE, in_fd, 0);
                close(in_fd);
 
@@ -533,48 +831,162 @@ int git_config_set_multivar(const char* key, const char* value,
 
                for (i = 0, copy_begin = 0; i < store.seen; i++) {
                        if (store.offset[i] == 0) {
-                               store.offset[i] = copy_end = st.st_size;
+                               store.offset[i] = copy_end = contents_sz;
                        } else if (store.state != KEY_SEEN) {
                                copy_end = store.offset[i];
                        } else
                                copy_end = find_beginning_of_line(
-                                       contents, st.st_size,
+                                       contents, contents_sz,
                                        store.offset[i]-2, &new_line);
 
                        /* write the first part of the config */
                        if (copy_end > copy_begin) {
-                               write(fd, contents + copy_begin,
-                               copy_end - copy_begin);
-                               if (new_line)
-                                       write(fd, "\n", 1);
+                               if (write_in_full(fd, contents + copy_begin,
+                                                 copy_end - copy_begin) <
+                                   copy_end - copy_begin)
+                                       goto write_err_out;
+                               if (new_line &&
+                                   write_in_full(fd, "\n", 1) != 1)
+                                       goto write_err_out;
                        }
                        copy_begin = store.offset[i];
                }
 
                /* write the pair (value == NULL means unset) */
                if (value != NULL) {
-                       if (store.state == START)
-                               store_write_section(fd, key);
-                       store_write_pair(fd, key, value);
+                       if (store.state == START) {
+                               if (!store_write_section(fd, key))
+                                       goto write_err_out;
+                       }
+                       if (!store_write_pair(fd, key, value))
+                               goto write_err_out;
                }
 
                /* write the rest of the config */
-               if (copy_begin < st.st_size)
-                       write(fd, contents + copy_begin,
-                               st.st_size - copy_begin);
+               if (copy_begin < contents_sz)
+                       if (write_in_full(fd, contents + copy_begin,
+                                         contents_sz - copy_begin) <
+                           contents_sz - copy_begin)
+                               goto write_err_out;
+
+               munmap(contents, contents_sz);
+               unlink(config_filename);
+       }
 
-               munmap(contents, st.st_size);
-               unlink(config_file);
+       if (rename(lock_file, config_filename) < 0) {
+               fprintf(stderr, "Could not rename the lock file?\n");
+               ret = 4;
+               goto out_free;
        }
 
-       close(fd);
+       ret = 0;
 
-       if (rename(lock_file, config_file) < 0) {
-               fprintf(stderr, "Could not rename the lock file?\n");
-               return 4;
+out_free:
+       if (0 <= fd)
+               close(fd);
+       free(config_filename);
+       if (lock_file) {
+               unlink(lock_file);
+               free(lock_file);
        }
+       return ret;
+
+write_err_out:
+       ret = write_error();
+       goto out_free;
 
-       return 0;
 }
 
+static int section_name_match (const char *buf, const char *name)
+{
+       int i = 0, j = 0, dot = 0;
+       for (; buf[i] && buf[i] != ']'; i++) {
+               if (!dot && isspace(buf[i])) {
+                       dot = 1;
+                       if (name[j++] != '.')
+                               break;
+                       for (i++; isspace(buf[i]); i++)
+                               ; /* do nothing */
+                       if (buf[i] != '"')
+                               break;
+                       continue;
+               }
+               if (buf[i] == '\\' && dot)
+                       i++;
+               else if (buf[i] == '"' && dot) {
+                       for (i++; isspace(buf[i]); i++)
+                               ; /* do_nothing */
+                       break;
+               }
+               if (buf[i] != name[j++])
+                       break;
+       }
+       return (buf[i] == ']' && name[j] == 0);
+}
+
+/* if new_name == NULL, the section is removed instead */
+int git_config_rename_section(const char *old_name, const char *new_name)
+{
+       int ret = 0, remove = 0;
+       char *config_filename;
+       struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
+       int out_fd;
+       char buf[1024];
+
+       config_filename = getenv(CONFIG_ENVIRONMENT);
+       if (!config_filename) {
+               config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
+               if (!config_filename)
+                       config_filename  = git_path("config");
+       }
+       config_filename = xstrdup(config_filename);
+       out_fd = hold_lock_file_for_update(lock, config_filename, 0);
+       if (out_fd < 0) {
+               ret = error("Could not lock config file!");
+               goto out;
+       }
+
+       if (!(config_file = fopen(config_filename, "rb"))) {
+               /* no config file means nothing to rename, no error */
+               goto unlock_and_out;
+       }
+
+       while (fgets(buf, sizeof(buf), config_file)) {
+               int i;
+               int length;
+               for (i = 0; buf[i] && isspace(buf[i]); i++)
+                       ; /* do nothing */
+               if (buf[i] == '[') {
+                       /* it's a section */
+                       if (section_name_match (&buf[i+1], old_name)) {
+                               ret++;
+                               if (new_name == NULL) {
+                                       remove = 1;
+                                       continue;
+                               }
+                               store.baselen = strlen(new_name);
+                               if (!store_write_section(out_fd, new_name)) {
+                                       ret = write_error();
+                                       goto out;
+                               }
+                               continue;
+                       }
+                       remove = 0;
+               }
+               if (remove)
+                       continue;
+               length = strlen(buf);
+               if (write_in_full(out_fd, buf, length) != length) {
+                       ret = write_error();
+                       goto out;
+               }
+       }
+       fclose(config_file);
+ unlock_and_out:
+       if (close(out_fd) || commit_lock_file(lock) < 0)
+                       ret = error("Cannot commit config file!");
+ out:
+       free(config_filename);
+       return ret;
+}