Simplify commit and tag parsing

* Use skip_prefix to avoid magic numbers in the code.
* Use xcalloc() instead of xmalloc(), followed by manual initialization.
* Split out line splitting.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

1 files changed, 42 insertions, 72 deletions

diff --git a/parsing.c b/parsing.c
index 53c29bb..0db181b 100644
--- a/parsing.c
+++ b/parsing.c
@@ -118,45 +118,50 @@ static const char *reencode(char **txt, const char *src_enc, const char *dst_enc
 }
 #endif
 
+static const char *next_header_line(const char *p)
+{
+        p = strchr(p, '\n');
+        if (!p)
+                return NULL;
+        return p + 1;
+}
+
+static int end_of_header(const char *p)
+{
+        return !p || (*p == '\n');
+}
+
 struct commitinfo *cgit_parse_commit(struct commit *commit)
 {
+        const int sha1hex_len = 40;
         struct commitinfo *ret;
         const char *p = get_cached_commit_buffer(commit, NULL);
         const char *t;
 
-        ret = xmalloc(sizeof(*ret));
+        ret = xcalloc(1, sizeof(struct commitinfo));
         ret->commit = commit;
-        ret->author = NULL;
-        ret->author_email = NULL;
-        ret->committer = NULL;
-        ret->committer_email = NULL;
-        ret->subject = NULL;
-        ret->msg = NULL;
-        ret->msg_encoding = NULL;
-
-        if (p == NULL)
+
+        if (!p)
                 return ret;
 
-        if (!starts_with(p, "tree "))
+        if (!skip_prefix(p, "tree ", &p))
                 die("Bad commit: %s", sha1_to_hex(commit->object.sha1));
-        else
-                p += 46; // "tree " + hex[40] + "\n"
+        p += sha1hex_len + 1;
 
-        while (starts_with(p, "parent "))
-                p += 48; // "parent " + hex[40] + "\n"
+        while (skip_prefix(p, "parent ", &p))
+                p += sha1hex_len + 1;
 
-        if (p && starts_with(p, "author ")) {
-                p = parse_user(p + 7, &ret->author, &ret->author_email,
+        if (p && skip_prefix(p, "author ", &p)) {
+                p = parse_user(p, &ret->author, &ret->author_email,
                         &ret->author_date);
         }
 
-        if (p && starts_with(p, "committer ")) {
-                p = parse_user(p + 10, &ret->committer, &ret->committer_email,
+        if (p && skip_prefix(p, "committer ", &p)) {
+                p = parse_user(p, &ret->committer, &ret->committer_email,
                         &ret->committer_date);
         }
 
-        if (p && starts_with(p, "encoding ")) {
-                p += 9;
+        if (p && skip_prefix(p, "encoding ", &p)) {
                 t = strchr(p, '\n');
                 if (t) {
                         ret->msg_encoding = substr(p, t + 1);
@@ -164,38 +169,21 @@ struct commitinfo *cgit_parse_commit(struct commit *commit)
                 }
         }
 
-        /* if no special encoding is found, assume UTF-8 */
         if (!ret->msg_encoding)
                 ret->msg_encoding = xstrdup("UTF-8");
 
-        // skip unknown header fields
-        while (p && *p && (*p != '\n')) {
-                p = strchr(p, '\n');
-                if (p)
-                        p++;
-        }
-
-        // skip empty lines between headers and message
+        while (!end_of_header(p))
+                p = next_header_line(p);
         while (p && *p == '\n')
                 p++;
-
         if (!p)
                 return ret;
 
-        t = strchr(p, '\n');
-        if (t) {
-                ret->subject = substr(p, t);
-                p = t + 1;
-
-                while (p && *p == '\n') {
-                        p = strchr(p, '\n');
-                        if (p)
-                                p++;
-                }
-                if (p)
-                        ret->msg = xstrdup(p);
-        } else
-                ret->subject = xstrdup(p);
+        t = strchrnul(p, '\n');
+        ret->subject = substr(p, t);
+        while (*t == '\n')
+                t++;
+        ret->msg = xstrdup(t);
 
         reencode(&ret->author, ret->msg_encoding, PAGE_ENCODING);
         reencode(&ret->author_email, ret->msg_encoding, PAGE_ENCODING);
@@ -207,49 +195,31 @@ struct commitinfo *cgit_parse_commit(struct commit *commit)
         return ret;
 }
 
-
 struct taginfo *cgit_parse_tag(struct tag *tag)
 {
         void *data;
         enum object_type type;
         unsigned long size;
         const char *p;
-        struct taginfo *ret;
+        struct taginfo *ret = NULL;
 
         data = read_sha1_file(tag->object.sha1, &type, &size);
-        if (!data || type != OBJ_TAG) {
-                free(data);
-                return 0;
-        }
+        if (!data || type != OBJ_TAG)
+                goto cleanup;
 
-        ret = xmalloc(sizeof(*ret));
-        ret->tagger = NULL;
-        ret->tagger_email = NULL;
-        ret->tagger_date = 0;
-        ret->msg = NULL;
+        ret = xcalloc(1, sizeof(struct taginfo));
 
-        p = data;
-
-        while (p && *p) {
-                if (*p == '\n')
-                        break;
-
-                if (starts_with(p, "tagger ")) {
-                        p = parse_user(p + 7, &ret->tagger, &ret->tagger_email,
+        for (p = data; !end_of_header(p); p = next_header_line(p)) {
+                if (skip_prefix(p, "tagger ", &p)) {
+                        p = parse_user(p, &ret->tagger, &ret->tagger_email,
                                 &ret->tagger_date);
-                } else {
-                        p = strchr(p, '\n');
-                        if (p)
-                                p++;
                 }
         }
 
-        // skip empty lines between headers and message
-        while (p && *p == '\n')
-                p++;
-
         if (p && *p)
                 ret->msg = xstrdup(p);
+
+cleanup:
         free(data);
         return ret;
 }