Merge branch 'jc/reflog-reverse-walk'

An internal function used to implement "git checkout @{-1}" was
hard to use correctly.

* jc/reflog-reverse-walk:
refs.c: fix fread error handling
reflog: add for_each_reflog_ent_reverse() API
for_each_recent_reflog_ent(): simplify opening of a reflog file
for_each_reflog_ent(): extract a helper to process a single entry

diff --git a/refs.c b/refs.c
index e2b760d0baffd6db6b49e6014a58efa062f1a119..de2d8eb866062649a0d0f23a77e350bca1a182cd 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -2332,59 +2332,117 @@ int read_ref_at(const char *refname, unsigned long at_time, int cnt,
        return 1;
 }
 
-int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long ofs, void *cb_data)
+static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
+{
+       unsigned char osha1[20], nsha1[20];
+       char *email_end, *message;
+       unsigned long timestamp;
+       int tz;
+
+       /* old SP new SP name <email> SP time TAB msg LF */
+       if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
+           get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
+           get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
+           !(email_end = strchr(sb->buf + 82, '>')) ||
+           email_end[1] != ' ' ||
+           !(timestamp = strtoul(email_end + 2, &message, 10)) ||
+           !message || message[0] != ' ' ||
+           (message[1] != '+' && message[1] != '-') ||
+           !isdigit(message[2]) || !isdigit(message[3]) ||
+           !isdigit(message[4]) || !isdigit(message[5]))
+               return 0; /* corrupt? */
+       email_end[1] = '\0';
+       tz = strtol(message + 1, NULL, 10);
+       if (message[6] != '\t')
+               message += 6;
+       else
+               message += 7;
+       return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
+}
+
+static char *find_beginning_of_line(char *bob, char *scan)
+{
+       while (bob < scan && *(--scan) != '\n')
+               ; /* keep scanning backwards */
+       /*
+        * Return either beginning of the buffer, or LF at the end of
+        * the previous line.
+        */
+       return scan;
+}
+
+int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
 {
-       const char *logfile;
-       FILE *logfp;
        struct strbuf sb = STRBUF_INIT;
-       int ret = 0;
+       FILE *logfp;
+       long pos;
+       int ret = 0, at_tail = 1;
 
-       logfile = git_path("logs/%s", refname);
-       logfp = fopen(logfile, "r");
+       logfp = fopen(git_path("logs/%s", refname), "r");
        if (!logfp)
                return -1;
 
-       if (ofs) {
-               struct stat statbuf;
-               if (fstat(fileno(logfp), &statbuf) ||
-                   statbuf.st_size < ofs ||
-                   fseek(logfp, -ofs, SEEK_END) ||
-                   strbuf_getwholeline(&sb, logfp, '\n')) {
-                       fclose(logfp);
-                       strbuf_release(&sb);
-                       return -1;
+       /* Jump to the end */
+       if (fseek(logfp, 0, SEEK_END) < 0)
+               return error("cannot seek back reflog for %s: %s",
+                            refname, strerror(errno));
+       pos = ftell(logfp);
+       while (!ret && 0 < pos) {
+               int cnt;
+               size_t nread;
+               char buf[BUFSIZ];
+               char *endp, *scanp;
+
+               /* Fill next block from the end */
+               cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
+               if (fseek(logfp, pos - cnt, SEEK_SET))
+                       return error("cannot seek back reflog for %s: %s",
+                                    refname, strerror(errno));
+               nread = fread(buf, cnt, 1, logfp);
+               if (nread != 1)
+                       return error("cannot read %d bytes from reflog for %s: %s",
+                                    cnt, refname, strerror(errno));
+               pos -= cnt;
+
+               scanp = endp = buf + cnt;
+               if (at_tail && scanp[-1] == '\n')
+                       /* Looking at the final LF at the end of the file */
+                       scanp--;
+               at_tail = 0;
+
+               while (buf < scanp) {
+                       /*
+                        * terminating LF of the previous line, or the beginning
+                        * of the buffer.
+                        */
+                       char *bp;
+
+                       bp = find_beginning_of_line(buf, scanp);
+
+                       if (*bp != '\n') {
+                               strbuf_splice(&sb, 0, 0, buf, endp - buf);
+                               if (pos)
+                                       break; /* need to fill another block */
+                               scanp = buf - 1; /* leave loop */
+                       } else {
+                               /*
+                                * (bp + 1) thru endp is the beginning of the
+                                * current line we have in sb
+                                */
+                               strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
+                               scanp = bp;
+                               endp = bp + 1;
+                       }
+                       ret = show_one_reflog_ent(&sb, fn, cb_data);
+                       strbuf_reset(&sb);
+                       if (ret)
+                               break;
                }
-       }
 
-       while (!strbuf_getwholeline(&sb, logfp, '\n')) {
-               unsigned char osha1[20], nsha1[20];
-               char *email_end, *message;
-               unsigned long timestamp;
-               int tz;
-
-               /* old SP new SP name <email> SP time TAB msg LF */
-               if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
-                   get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
-                   get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
-                   !(email_end = strchr(sb.buf + 82, '>')) ||
-                   email_end[1] != ' ' ||
-                   !(timestamp = strtoul(email_end + 2, &message, 10)) ||
-                   !message || message[0] != ' ' ||
-                   (message[1] != '+' && message[1] != '-') ||
-                   !isdigit(message[2]) || !isdigit(message[3]) ||
-                   !isdigit(message[4]) || !isdigit(message[5]))
-                       continue; /* corrupt? */
-               email_end[1] = '\0';
-               tz = strtol(message + 1, NULL, 10);
-               if (message[6] != '\t')
-                       message += 6;
-               else
-                       message += 7;
-               ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
-                        cb_data);
-               if (ret)
-                       break;
        }
+       if (!ret && sb.len)
+               ret = show_one_reflog_ent(&sb, fn, cb_data);
+
        fclose(logfp);
        strbuf_release(&sb);
        return ret;
@@ -2392,9 +2450,20 @@ int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long
 
 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
 {
-       return for_each_recent_reflog_ent(refname, fn, 0, cb_data);
-}
+       FILE *logfp;
+       struct strbuf sb = STRBUF_INIT;
+       int ret = 0;
+
+       logfp = fopen(git_path("logs/%s", refname), "r");
+       if (!logfp)
+               return -1;
 
+       while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
+               ret = show_one_reflog_ent(&sb, fn, cb_data);
+       fclose(logfp);
+       strbuf_release(&sb);
+       return ret;
+}
 /*
  * Call fn for each reflog in the namespace indicated by name.  name
  * must be empty or end with '/'.  Name will be used as a scratch

diff --git a/refs.h b/refs.h
index 1b2e2d3a98dea86bbe54dd21782ce58681636c32..a35eafc4ee15493c1473d71b5c2e83a1f9137c1a 100644 (file)
--- a/refs.h
+++ b/refs.h
@@ -103,7 +103,7 @@ extern int read_ref_at(const char *refname, unsigned long at_time, int cnt,
 /* iterate over reflog entries */
 typedef int each_reflog_ent_fn(unsigned char *osha1, unsigned char *nsha1, const char *, unsigned long, int, const char *, void *);
 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data);
-int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long, void *cb_data);
+int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data);
 
 /*
  * Calls the specified function for each reflog file until it returns nonzero,

diff --git a/sha1_name.c b/sha1_name.c
index c50630a3ea793e0cfd2510b8813129a1685428f4..2fbda48e02f167d08aa19210951712b85f40b602 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -856,8 +856,8 @@ static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 }
 
 struct grab_nth_branch_switch_cbdata {
-       long cnt, alloc;
-       struct strbuf *buf;
+       int remaining;
+       struct strbuf buf;
 };
 
 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
@@ -867,7 +867,6 @@ static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
        struct grab_nth_branch_switch_cbdata *cb = cb_data;
        const char *match = NULL, *target = NULL;
        size_t len;
-       int nth;
 
        if (!prefixcmp(message, "checkout: moving from ")) {
                match = message + strlen("checkout: moving from ");
@@ -876,11 +875,12 @@ static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 
        if (!match || !target)
                return 0;
-
-       len = target - match;
-       nth = cb->cnt++ % cb->alloc;
-       strbuf_reset(&cb->buf[nth]);
-       strbuf_add(&cb->buf[nth], match, len);
+       if (--(cb->remaining) == 0) {
+               len = target - match;
+               strbuf_reset(&cb->buf);
+               strbuf_add(&cb->buf, match, len);
+               return 1; /* we are done */
+       }
        return 0;
 }
 
@@ -891,7 +891,7 @@ static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 {
        long nth;
-       int i, retval;
+       int retval;
        struct grab_nth_branch_switch_cbdata cb;
        const char *brace;
        char *num_end;
@@ -901,34 +901,22 @@ static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
        brace = strchr(name, '}');
        if (!brace)
                return -1;
-       nth = strtol(name+3, &num_end, 10);
+       nth = strtol(name + 3, &num_end, 10);
        if (num_end != brace)
                return -1;
        if (nth <= 0)
                return -1;
-       cb.alloc = nth;
-       cb.buf = xmalloc(nth * sizeof(struct strbuf));
-       for (i = 0; i < nth; i++)
-               strbuf_init(&cb.buf[i], 20);
-       cb.cnt = 0;
+       cb.remaining = nth;
+       strbuf_init(&cb.buf, 20);
+
        retval = 0;
-       for_each_recent_reflog_ent("HEAD", grab_nth_branch_switch, 40960, &cb);
-       if (cb.cnt < nth) {
-               cb.cnt = 0;
-               for_each_reflog_ent("HEAD", grab_nth_branch_switch, &cb);
+       if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
+               strbuf_reset(buf);
+               strbuf_add(buf, cb.buf.buf, cb.buf.len);
+               retval = brace - name + 1;
        }
-       if (cb.cnt < nth)
-               goto release_return;
-       i = cb.cnt % nth;
-       strbuf_reset(buf);
-       strbuf_add(buf, cb.buf[i].buf, cb.buf[i].len);
-       retval = brace-name+1;
-
-release_return:
-       for (i = 0; i < nth; i++)
-               strbuf_release(&cb.buf[i]);
-       free(cb.buf);
 
+       strbuf_release(&cb.buf);
        return retval;
 }