Merge branch 'jk/diagnose-config-mmap-failure' into maint

The configuration reader/writer uses mmap(2) interface to access
the files; when we find a directory, it barfed with "Out of memory?".

* jk/diagnose-config-mmap-failure:
  xmmap(): drop "Out of memory?"
  config.c: rewrite ENODEV into EISDIR when mmap fails
  config.c: avoid xmmap error messages
  config.c: fix mmap leak when writing config
  read-cache.c: drop PROT_WRITE from mmap of index

1 files changed, 16 insertions, 6 deletions

diff --git a/config.c b/config.c
index 286907b..27a73c8 100644
--- a/config.c
+++ b/config.c
@@ -1937,6 +1937,8 @@ int git_config_set_multivar_in_file(const char *config_filename,
 	int ret;
 	struct lock_file *lock = NULL;
 	char *filename_buf = NULL;
+	char *contents = NULL;
+	size_t contents_sz;
 
 	/* parse-key returns negative; flip the sign to feed exit(3) */
 	ret = 0 - git_config_parse_key(key, &store.key, &store.baselen);
@@ -1986,8 +1988,7 @@ int git_config_set_multivar_in_file(const char *config_filename,
 			goto write_err_out;
 	} else {
 		struct stat st;
-		char *contents;
-		size_t contents_sz, copy_begin, copy_end;
+		size_t copy_begin, copy_end;
 		int i, new_line = 0;
 
 		if (value_regex == NULL)
@@ -2050,8 +2051,17 @@ int git_config_set_multivar_in_file(const char *config_filename,
 
 		fstat(in_fd, &st);
 		contents_sz = xsize_t(st.st_size);
-		contents = xmmap(NULL, contents_sz, PROT_READ,
-			MAP_PRIVATE, in_fd, 0);
+		contents = xmmap_gently(NULL, contents_sz, PROT_READ,
+					MAP_PRIVATE, in_fd, 0);
+		if (contents == MAP_FAILED) {
+			if (errno == ENODEV && S_ISDIR(st.st_mode))
+				errno = EISDIR;
+			error("unable to mmap '%s': %s",
+			      config_filename, strerror(errno));
+			ret = CONFIG_INVALID_FILE;
+			contents = NULL;
+			goto out_free;
+		}
 		close(in_fd);
 
 		if (chmod(lock->filename.buf, st.st_mode & 07777) < 0) {
@@ -2106,8 +2116,6 @@ int git_config_set_multivar_in_file(const char *config_filename,
 					  contents_sz - copy_begin) <
 			    contents_sz - copy_begin)
 				goto write_err_out;
-
-		munmap(contents, contents_sz);
 	}
 
 	if (commit_lock_file(lock) < 0) {
@@ -2133,6 +2141,8 @@ out_free:
 	if (lock)
 		rollback_lock_file(lock);
 	free(filename_buf);
+	if (contents)
+		munmap(contents, contents_sz);
 	return ret;
 
 write_err_out: