[PATCH v17 13/48] refs.c: make resolve_ref_unsafe set errno to something meaningful on error

[Ronnie Sahlberg]

Making errno when returning from resolve_ref_unsafe() meaningful,
which should fix

 * a bug in lock_ref_sha1_basic, where it assumes EISDIR
   means it failed due to a directory being in the way

Signed-off-by: Ronnie Sahlberg <sahlb...@google.com>
---
 cache.h |  2 +-
 refs.c  | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/cache.h b/cache.h
index 19b0963..0c2a9aa 100644
--- a/cache.h
+++ b/cache.h
@@ -980,7 +980,7 @@ extern int read_ref(const char *refname, unsigned char 
*sha1);
  * NULL.  If more than MAXDEPTH recursive symbolic lookups are needed,
  * give up and return NULL.
  *
- * errno is sometimes set on errors, but not always.
+ * errno is set to something meaningful on error.
  */
 extern const char *resolve_ref_unsafe(const char *ref, unsigned char *sha1, 
int reading, int *flag);
 extern char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, 
int *flag);
diff --git a/refs.c b/refs.c
index dc9de2c..a4c728c 100644
--- a/refs.c
+++ b/refs.c
@@ -1323,6 +1323,7 @@ static const char *handle_missing_loose_ref(const char 
*refname,
        }
 }
 
+/* This function needs to return a meaningful errno on failure */
 const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int 
reading, int *flag)
 {
        int depth = MAXDEPTH;
@@ -1333,8 +1334,10 @@ const char *resolve_ref_unsafe(const char *refname, 
unsigned char *sha1, int rea
        if (flag)
                *flag = 0;
 
-       if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
+       if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+               errno = EINVAL;
                return NULL;
+       }
 
        for (;;) {
                char path[PATH_MAX];
@@ -1342,8 +1345,10 @@ const char *resolve_ref_unsafe(const char *refname, 
unsigned char *sha1, int rea
                char *buf;
                int fd;
 
-               if (--depth < 0)
+               if (--depth < 0) {
+                       errno = ELOOP;
                        return NULL;
+               }
 
                git_snpath(path, sizeof(path), "%s", refname);
 
@@ -1405,9 +1410,13 @@ const char *resolve_ref_unsafe(const char *refname, 
unsigned char *sha1, int rea
                                return NULL;
                }
                len = read_in_full(fd, buffer, sizeof(buffer)-1);
+               if (len < 0) {
+                       int save_errno = errno;
+                       close(fd);
+                       errno = save_errno;
+                       return NULL;
+               }
                close(fd);
-               if (len < 0)
-                       return NULL;
                while (len && isspace(buffer[len-1]))
                        len--;
                buffer[len] = '\0';
@@ -1424,6 +1433,7 @@ const char *resolve_ref_unsafe(const char *refname, 
unsigned char *sha1, int rea
                            (buffer[40] != '\0' && !isspace(buffer[40]))) {
                                if (flag)
                                        *flag |= REF_ISBROKEN;
+                               errno = EINVAL;
                                return NULL;
                        }
                        return refname;
@@ -1436,6 +1446,7 @@ const char *resolve_ref_unsafe(const char *refname, 
unsigned char *sha1, int rea
                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
                        if (flag)
                                *flag |= REF_ISBROKEN;
+                       errno = EINVAL;
                        return NULL;
                }
                refname = strcpy(refname_buffer, buf);
-- 
2.0.0.282.g3799eda.dirty

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