c064e10580d5e1f7185f3f32ee19319292f6b43d
   1/*
   2 * Copyright (C) 2005 Junio C Hamano
   3 */
   4#include <sys/types.h>
   5#include <sys/wait.h>
   6#include "cache.h"
   7#include "diff.h"
   8
   9static char *diff_opts = "-pu";
  10
  11static const char *external_diff(void)
  12{
  13        static char *external_diff_cmd = NULL;
  14        static int done_preparing = 0;
  15
  16        if (done_preparing)
  17                return external_diff_cmd;
  18
  19        /*
  20         * Default values above are meant to match the
  21         * Linux kernel development style.  Examples of
  22         * alternative styles you can specify via environment
  23         * variables are:
  24         *
  25         * GIT_DIFF_OPTS="-c";
  26         */
  27        if (getenv("GIT_EXTERNAL_DIFF"))
  28                external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
  29
  30        /* In case external diff fails... */
  31        diff_opts = getenv("GIT_DIFF_OPTS") ? : diff_opts;
  32
  33        done_preparing = 1;
  34        return external_diff_cmd;
  35}
  36
  37/* Help to copy the thing properly quoted for the shell safety.
  38 * any single quote is replaced with '\'', and the caller is
  39 * expected to enclose the result within a single quote pair.
  40 *
  41 * E.g.
  42 *  original     sq_expand     result
  43 *  name     ==> name      ==> 'name'
  44 *  a b      ==> a b       ==> 'a b'
  45 *  a'b      ==> a'\''b    ==> 'a'\''b'
  46 */
  47static char *sq_expand(const char *src)
  48{
  49        static char *buf = NULL;
  50        int cnt, c;
  51        const char *cp;
  52        char *bp;
  53
  54        /* count bytes needed to store the quoted string. */ 
  55        for (cnt = 1, cp = src; *cp; cnt++, cp++)
  56                if (*cp == '\'')
  57                        cnt += 3;
  58
  59        buf = xmalloc(cnt);
  60        bp = buf;
  61        while ((c = *src++)) {
  62                if (c != '\'')
  63                        *bp++ = c;
  64                else {
  65                        bp = strcpy(bp, "'\\''");
  66                        bp += 4;
  67                }
  68        }
  69        *bp = 0;
  70        return buf;
  71}
  72
  73static struct diff_tempfile {
  74        const char *name;
  75        char hex[41];
  76        char mode[10];
  77        char tmp_path[50];
  78} diff_temp[2];
  79
  80static void builtin_diff(const char *name,
  81                         struct diff_tempfile *temp)
  82{
  83        int i, next_at;
  84        const char *diff_cmd = "diff -L'%s%s%s' -L'%s%s%s'";
  85        const char *diff_arg  = "'%s' '%s'";
  86        const char *input_name_sq[2];
  87        const char *path0[2];
  88        const char *path1[2];
  89        char mode[2][20];
  90        const char *name_sq = sq_expand(name);
  91        char *cmd;
  92        
  93        /* diff_cmd and diff_arg have 8 %s in total which makes
  94         * the sum of these strings 16 bytes larger than required.
  95         * we use 2 spaces around diff-opts, and we need to count
  96         * terminating NUL, so we subtract 13 here.
  97         */
  98        int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
  99                        strlen(diff_arg) - 13);
 100        for (i = 0; i < 2; i++) {
 101                input_name_sq[i] = sq_expand(temp[i].name);
 102                if (!strcmp(temp[i].name, "/dev/null")) {
 103                        path0[i] = "/dev/null";
 104                        path1[i] = "";
 105                        mode[i][0] = 0;
 106                } else {
 107                        path0[i] = i ? "l/" : "k/";
 108                        path1[i] = name_sq;
 109                        sprintf(mode[i], "  (mode:%s)", temp[i].mode);
 110                }
 111                cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
 112                             strlen(mode[i]) + strlen(input_name_sq[i]));
 113        }
 114
 115        cmd = xmalloc(cmd_size);
 116
 117        next_at = 0;
 118        next_at += snprintf(cmd+next_at, cmd_size-next_at,
 119                            diff_cmd,
 120                            path0[0], path1[0], mode[0],
 121                            path0[1], path1[1], mode[1]);
 122        next_at += snprintf(cmd+next_at, cmd_size-next_at,
 123                            " %s ", diff_opts);
 124        next_at += snprintf(cmd+next_at, cmd_size-next_at,
 125                            diff_arg, input_name_sq[0], input_name_sq[1]);
 126
 127        execlp("/bin/sh","sh", "-c", cmd, NULL);
 128}
 129
 130static void prepare_temp_file(const char *name,
 131                              struct diff_tempfile *temp,
 132                              struct diff_spec *one)
 133{
 134        static unsigned char null_sha1[20] = { 0, };
 135
 136        if (!one->file_valid) {
 137        not_a_valid_file:
 138                temp->name = "/dev/null";
 139                strcpy(temp->hex, ".");
 140                strcpy(temp->mode, ".");
 141                return;
 142        }
 143
 144        if (one->sha1_valid &&
 145            !memcmp(one->u.sha1, null_sha1, sizeof(null_sha1))) {
 146                one->sha1_valid = 0;
 147                one->u.name = name;
 148        }
 149
 150        if (!one->sha1_valid) {
 151                struct stat st;
 152                temp->name = one->u.name;
 153                if (stat(temp->name, &st) < 0) {
 154                        if (errno == ENOENT)
 155                                goto not_a_valid_file;
 156                        die("stat(%s): %s", temp->name, strerror(errno));
 157                }
 158                strcpy(temp->hex, ".");
 159                sprintf(temp->mode, "%06o",
 160                        S_IFREG |ce_permissions(st.st_mode));
 161        }
 162        else {
 163                int fd;
 164                void *blob;
 165                char type[20];
 166                unsigned long size;
 167
 168                blob = read_sha1_file(one->u.sha1, type, &size);
 169                if (!blob || strcmp(type, "blob"))
 170                        die("unable to read blob object for %s (%s)",
 171                            name, sha1_to_hex(one->u.sha1));
 172
 173                strcpy(temp->tmp_path, ".diff_XXXXXX");
 174                fd = mkstemp(temp->tmp_path);
 175                if (fd < 0)
 176                        die("unable to create temp-file");
 177                if (write(fd, blob, size) != size)
 178                        die("unable to write temp-file");
 179                close(fd);
 180                free(blob);
 181                temp->name = temp->tmp_path;
 182                strcpy(temp->hex, sha1_to_hex(one->u.sha1));
 183                temp->hex[40] = 0;
 184                sprintf(temp->mode, "%06o", one->mode);
 185        }
 186}
 187
 188static void remove_tempfile(void)
 189{
 190        int i;
 191
 192        for (i = 0; i < 2; i++)
 193                if (diff_temp[i].name == diff_temp[i].tmp_path) {
 194                        unlink(diff_temp[i].name);
 195                        diff_temp[i].name = NULL;
 196                }
 197}
 198
 199/* An external diff command takes:
 200 *
 201 * diff-cmd name infile1 infile1-sha1 infile1-mode \
 202 *               infile2 infile2-sha1 infile2-mode.
 203 *
 204 */
 205void run_external_diff(const char *name,
 206                       struct diff_spec *one,
 207                       struct diff_spec *two)
 208{
 209        struct diff_tempfile *temp = diff_temp;
 210        int pid, status;
 211        static int atexit_asked = 0;
 212
 213        if (one && two) {
 214                prepare_temp_file(name, &temp[0], one);
 215                prepare_temp_file(name, &temp[1], two);
 216                if (! atexit_asked &&
 217                    (temp[0].name == temp[0].tmp_path ||
 218                     temp[1].name == temp[1].tmp_path)) {
 219                        atexit_asked = 1;
 220                        atexit(remove_tempfile);
 221                }
 222        }
 223
 224        fflush(NULL);
 225        pid = fork();
 226        if (pid < 0)
 227                die("unable to fork");
 228        if (!pid) {
 229                const char *pgm = external_diff();
 230                if (pgm) {
 231                        if (one && two)
 232                                execlp(pgm, pgm,
 233                                       name,
 234                                       temp[0].name, temp[0].hex, temp[0].mode,
 235                                       temp[1].name, temp[1].hex, temp[1].mode,
 236                                       NULL);
 237                        else
 238                                execlp(pgm, pgm, name, NULL);
 239                }
 240                /*
 241                 * otherwise we use the built-in one.
 242                 */
 243                if (one && two)
 244                        builtin_diff(name, temp);
 245                else
 246                        printf("* Unmerged path %s\n", name);
 247                exit(0);
 248        }
 249        if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status))
 250                die("diff program failed");
 251
 252        remove_tempfile();
 253}
 254
 255void diff_addremove(int addremove, unsigned mode,
 256                    const unsigned char *sha1,
 257                    const char *base, const char *path)
 258{
 259        char concatpath[PATH_MAX];
 260        struct diff_spec spec[2], *one, *two;
 261
 262        memcpy(spec[0].u.sha1, sha1, 20);
 263        spec[0].mode = mode;
 264        spec[0].sha1_valid = spec[0].file_valid = 1;
 265        spec[1].file_valid = 0;
 266
 267        if (addremove == '+') {
 268                one = spec + 1; two = spec;
 269        } else {
 270                one = spec; two = one + 1;
 271        }
 272        
 273        if (path) {
 274                strcpy(concatpath, base);
 275                strcat(concatpath, path);
 276        }
 277        run_external_diff(path ? concatpath : base, one, two);
 278}
 279
 280void diff_change(unsigned old_mode, unsigned new_mode,
 281                 const unsigned char *old_sha1,
 282                 const unsigned char *new_sha1,
 283                 const char *base, const char *path) {
 284        char concatpath[PATH_MAX];
 285        struct diff_spec spec[2];
 286
 287        memcpy(spec[0].u.sha1, old_sha1, 20);
 288        spec[0].mode = old_mode;
 289        memcpy(spec[1].u.sha1, new_sha1, 20);
 290        spec[1].mode = new_mode;
 291        spec[0].sha1_valid = spec[0].file_valid = 1;
 292        spec[1].sha1_valid = spec[1].file_valid = 1;
 293
 294        if (path) {
 295                strcpy(concatpath, base);
 296                strcat(concatpath, path);
 297        }
 298        run_external_diff(path ? concatpath : base, &spec[0], &spec[1]);
 299}
 300
 301void diff_unmerge(const char *path)
 302{
 303        run_external_diff(path, NULL, NULL);
 304}