git-apply: create subdirectories leading up to a new file

Applying Andrew's latest patch-bomb showed us failing miserably if a new
subdirectory needed to be created..  That said, it's uncommon enough
that it's worth optimistically assuming it won't be needed, and then
creating the subdirectories only on failure.

diff --git a/apply.c b/apply.c
index 8a3ead6..af97537 100644 (file)
--- a/apply.c
+++ b/apply.c
@@ -1144,6 +1144,51 @@ static void add_index_file(const char *path, unsigned mode, void *buf, unsigned
                die("unable to add cache entry for %s", path);
 }
 
+static void create_subdirectories(const char *path)
+{
+       int len = strlen(path);
+       char *buf = xmalloc(len + 1);
+       const char *slash = path;
+
+       while ((slash = strchr(slash+1, '/')) != NULL) {
+               len = slash - path;
+               memcpy(buf, path, len);
+               buf[len] = 0;
+               if (mkdir(buf, 0755) < 0) {
+                       if (errno != EEXIST)
+                               break;
+               }
+       }
+       free(buf);
+}
+
+/*
+ * We optimistically assume that the directories exist,
+ * which is true 99% of the time anyway. If they don't,
+ * we create them and try again.
+ */
+static int create_regular_file(const char *path, unsigned int mode)
+{
+       int ret = open(path, O_WRONLY | O_CREAT | O_TRUNC, mode);
+
+       if (ret < 0 && errno == ENOENT) {
+               create_subdirectories(path);
+               ret = open(path, O_WRONLY | O_CREAT | O_TRUNC, mode);
+       }
+       return ret;
+}
+
+static int create_symlink(const char *buf, const char *path)
+{
+       int ret = symlink(buf, path);
+
+       if (ret < 0 && errno == ENOENT) {
+               create_subdirectories(path);
+               ret = symlink(buf, path);
+       }
+       return ret;
+}
+
 static void create_file(struct patch *patch)
 {
        const char *path = patch->new_name;
@@ -1156,7 +1201,7 @@ static void create_file(struct patch *patch)
        if (S_ISREG(mode)) {
                int fd;
                mode = (mode & 0100) ? 0777 : 0666;
-               fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, mode);
+               fd = create_regular_file(path, mode);
                if (fd < 0)
                        die("unable to create file %s (%s)", path, strerror(errno));
                if (write(fd, buf, size) != size)
@@ -1169,7 +1214,7 @@ static void create_file(struct patch *patch)
                if (size && buf[size-1] == '\n')
                        size--;
                buf[size] = 0;
-               if (symlink(buf, path) < 0)
+               if (create_symlink(buf, path) < 0)
                        die("unable to write symlink %s", path);
                add_index_file(path, mode, buf, size);
                return;