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authorLinus Torvalds <torvalds@linux-foundation.org>2008-12-17 17:36:40 (GMT)
committerJunio C Hamano <gitster@pobox.com>2008-12-17 21:36:30 (GMT)
commitb11b7e13f48ee283738e21fea9f775cd40ca0562 (patch)
treef1c1a1a271f018865e1b95b5885cb71520da13a8
parent53682f0c9e7545c6fa891896a5de4ad441a76147 (diff)
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Add generic 'strbuf_readlink()' helper function
It was already what 'git apply' did in read_old_data(), just export it as a real function, and make it be more generic. In particular, this handles the case of the lstat() st_size data not matching the readlink() return value properly (which apparently happens at least on NTFS under Linux). But as a result of this you could also use the new function without even knowing how big the link is going to be, and it will allocate an appropriately sized buffer. So we pass in the st_size of the link as just a hint, rather than a fixed requirement. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--builtin-apply.c6
-rw-r--r--strbuf.c27
-rw-r--r--strbuf.h1
3 files changed, 30 insertions, 4 deletions
diff --git a/builtin-apply.c b/builtin-apply.c
index 4c4d1e1..07244b0 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -1559,10 +1559,8 @@ static int read_old_data(struct stat *st, const char *path, struct strbuf *buf)
{
switch (st->st_mode & S_IFMT) {
case S_IFLNK:
- strbuf_grow(buf, st->st_size);
- if (readlink(path, buf->buf, st->st_size) != st->st_size)
- return -1;
- strbuf_setlen(buf, st->st_size);
+ if (strbuf_readlink(buf, path, st->st_size) < 0)
+ return error("unable to read symlink %s", path);
return 0;
case S_IFREG:
if (strbuf_read_file(buf, path, st->st_size) != st->st_size)
diff --git a/strbuf.c b/strbuf.c
index 13be67e..bdf4954 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -288,6 +288,33 @@ ssize_t strbuf_read(struct strbuf *sb, int fd, size_t hint)
return sb->len - oldlen;
}
+#define STRBUF_MAXLINK (2*PATH_MAX)
+
+int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
+{
+ if (hint < 32)
+ hint = 32;
+
+ while (hint < STRBUF_MAXLINK) {
+ int len;
+
+ strbuf_grow(sb, hint);
+ len = readlink(path, sb->buf, hint);
+ if (len < 0) {
+ if (errno != ERANGE)
+ break;
+ } else if (len < hint) {
+ strbuf_setlen(sb, len);
+ return 0;
+ }
+
+ /* .. the buffer was too small - try again */
+ hint *= 2;
+ }
+ strbuf_release(sb);
+ return -1;
+}
+
int strbuf_getline(struct strbuf *sb, FILE *fp, int term)
{
int ch;
diff --git a/strbuf.h b/strbuf.h
index b1670d9..89bd36e 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -124,6 +124,7 @@ extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
/* XXX: if read fails, any partial read is undone */
extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
extern int strbuf_read_file(struct strbuf *sb, const char *path, size_t hint);
+extern int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint);
extern int strbuf_getline(struct strbuf *, FILE *, int);