Merge branch 'jk/interpret-branch-name-fix'

Fix a handful of bugs around interpreting $branch@{upstream}
notation and its lookalike, when $branch part has interesting
characters, e.g. "@", and ":".

* jk/interpret-branch-name-fix:
interpret_branch_name: find all possible @-marks
interpret_branch_name: avoid @{upstream} past colon
interpret_branch_name: always respect "namelen" parameter
interpret_branch_name: rename "cp" variable to "at"
interpret_branch_name: factor out upstream handling

diff --combined sha1_name.c
index a5578f718ea092338eb16fbe7dbf867a98e82218,15854e35eced2c8b0c3e796aedcfbe553c6ac38f..6fca8692d2dd8875281fcb8379cc93805e647cea
--- 1/sha1_name.c
--- 2/sha1_name.c
+++ b/sha1_name.c
@@@ -430,7 -430,7 +430,7 @@@ static inline int upstream_mark(const c
  }
  
  static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
- static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf);
+ static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
  
  static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
  {
@@@ -451,9 -451,9 +451,9 @@@
        int at, reflog_len, nth_prior = 0;
  
        if (len == 40 && !get_sha1_hex(str, sha1)) {
 -              if (warn_on_object_refname_ambiguity) {
 +              if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
                        refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 -                      if (refs_found > 0 && warn_ambiguous_refs) {
 +                      if (refs_found > 0) {
                                warning(warn_msg, len, str);
                                if (advice_object_name_warning)
                                        fprintf(stderr, "%s\n", _(object_name_msg));
@@@ -492,7 -492,7 +492,7 @@@
                struct strbuf buf = STRBUF_INIT;
                int detached;
  
-               if (interpret_nth_prior_checkout(str, &buf) > 0) {
+               if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
                        detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
                        strbuf_release(&buf);
                        if (detached)
@@@ -546,7 -546,7 +546,7 @@@
                if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
                                &co_time, &co_tz, &co_cnt)) {
                        if (!len) {
 -                              if (!prefixcmp(real_ref, "refs/heads/")) {
 +                              if (starts_with(real_ref, "refs/heads/")) {
                                        str = real_ref + 11;
                                        len = strlen(real_ref + 11);
                                } else {
@@@ -581,6 -581,8 +581,6 @@@ static int get_parent(const char *name
        if (ret)
                return ret;
        commit = lookup_commit_reference(sha1);
 -      if (!commit)
 -              return -1;
        if (parse_commit(commit))
                return -1;
        if (!idx) {
@@@ -674,15 -676,15 +674,15 @@@ static int peel_onion(const char *name
                return -1;
  
        sp++; /* beginning of type name, or closing brace for empty */
 -      if (!prefixcmp(sp, "commit}"))
 +      if (starts_with(sp, "commit}"))
                expected_type = OBJ_COMMIT;
 -      else if (!prefixcmp(sp, "tag}"))
 +      else if (starts_with(sp, "tag}"))
                expected_type = OBJ_TAG;
 -      else if (!prefixcmp(sp, "tree}"))
 +      else if (starts_with(sp, "tree}"))
                expected_type = OBJ_TREE;
 -      else if (!prefixcmp(sp, "blob}"))
 +      else if (starts_with(sp, "blob}"))
                expected_type = OBJ_BLOB;
 -      else if (!prefixcmp(sp, "object}"))
 +      else if (starts_with(sp, "object}"))
                expected_type = OBJ_ANY;
        else if (sp[0] == '}')
                expected_type = OBJ_NONE;
@@@ -909,7 -911,7 +909,7 @@@ static int grab_nth_branch_switch(unsig
        const char *match = NULL, *target = NULL;
        size_t len;
  
 -      if (!prefixcmp(message, "checkout: moving from ")) {
 +      if (starts_with(message, "checkout: moving from ")) {
                match = message + strlen("checkout: moving from ");
                target = strstr(match, " to ");
        }
@@@ -929,7 -931,8 +929,8 @@@
   * Parse @{-N} syntax, return the number of characters parsed
   * if successful; otherwise signal an error with negative value.
   */
- static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
+ static int interpret_nth_prior_checkout(const char *name, int namelen,
+                                       struct strbuf *buf)
  {
        long nth;
        int retval;
@@@ -937,9 -940,11 +938,11 @@@
        const char *brace;
        char *num_end;
  
+       if (namelen < 4)
+               return -1;
        if (name[0] != '@' || name[1] != '{' || name[2] != '-')
                return -1;
-       brace = strchr(name, '}');
+       brace = memchr(name, '}', namelen);
        if (!brace)
                return -1;
        nth = strtol(name + 3, &num_end, 10);
@@@ -1012,7 -1017,7 +1015,7 @@@ static int interpret_empty_at(const cha
                return -1;
  
        /* make sure it's a single @, or @@{.*}, not @foo */
-       next = strchr(name + len + 1, '@');
+       next = memchr(name + len + 1, '@', namelen - len - 1);
        if (next && next[1] != '{')
                return -1;
        if (!next)
@@@ -1046,6 -1051,57 +1049,57 @@@ static int reinterpret(const char *name
        return ret - used + len;
  }
  
+ static void set_shortened_ref(struct strbuf *buf, const char *ref)
+ {
+       char *s = shorten_unambiguous_ref(ref, 0);
+       strbuf_reset(buf);
+       strbuf_addstr(buf, s);
+       free(s);
+ }
+ 
+ static const char *get_upstream_branch(const char *branch_buf, int len)
+ {
+       char *branch = xstrndup(branch_buf, len);
+       struct branch *upstream = branch_get(*branch ? branch : NULL);
+ 
+       /*
+        * Upstream can be NULL only if branch refers to HEAD and HEAD
+        * points to something different than a branch.
+        */
+       if (!upstream)
+               die(_("HEAD does not point to a branch"));
+       if (!upstream->merge || !upstream->merge[0]->dst) {
+               if (!ref_exists(upstream->refname))
+                       die(_("No such branch: '%s'"), branch);
+               if (!upstream->merge) {
+                       die(_("No upstream configured for branch '%s'"),
+                               upstream->name);
+               }
+               die(
+                       _("Upstream branch '%s' not stored as a remote-tracking branch"),
+                       upstream->merge[0]->src);
+       }
+       free(branch);
+ 
+       return upstream->merge[0]->dst;
+ }
+ 
+ static int interpret_upstream_mark(const char *name, int namelen,
+                                  int at, struct strbuf *buf)
+ {
+       int len;
+ 
+       len = upstream_mark(name + at, namelen - at);
+       if (!len)
+               return -1;
+ 
+       if (memchr(name, ':', at))
+               return -1;
+ 
+       set_shortened_ref(buf, get_upstream_branch(name, at));
+       return len + at;
+ }
+ 
  /*
   * This reads short-hand syntax that not only evaluates to a commit
   * object name, but also can act as if the end user spelled the name
@@@ -1069,10 -1125,9 +1123,9 @@@
   */
  int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
  {
-       char *cp;
-       struct branch *upstream;
-       int len = interpret_nth_prior_checkout(name, buf);
-       int tmp_len;
+       char *at;
+       const char *start;
+       int len = interpret_nth_prior_checkout(name, namelen, buf);
  
        if (!namelen)
                namelen = strlen(name);
@@@ -1086,44 -1141,20 +1139,20 @@@
                        return reinterpret(name, namelen, len, buf);
        }
  
-       cp = strchr(name, '@');
-       if (!cp)
-               return -1;
- 
-       len = interpret_empty_at(name, namelen, cp - name, buf);
-       if (len > 0)
-               return reinterpret(name, namelen, len, buf);
+       for (start = name;
+            (at = memchr(start, '@', namelen - (start - name)));
+            start = at + 1) {
  
-       tmp_len = upstream_mark(cp, namelen - (cp - name));
-       if (!tmp_len)
-               return -1;
+               len = interpret_empty_at(name, namelen, at - name, buf);
+               if (len > 0)
+                       return reinterpret(name, namelen, len, buf);
  
-       len = cp + tmp_len - name;
-       cp = xstrndup(name, cp - name);
-       upstream = branch_get(*cp ? cp : NULL);
-       /*
-        * Upstream can be NULL only if cp refers to HEAD and HEAD
-        * points to something different than a branch.
-        */
-       if (!upstream)
-               die(_("HEAD does not point to a branch"));
-       if (!upstream->merge || !upstream->merge[0]->dst) {
-               if (!ref_exists(upstream->refname))
-                       die(_("No such branch: '%s'"), cp);
-               if (!upstream->merge) {
-                       die(_("No upstream configured for branch '%s'"),
-                               upstream->name);
-               }
-               die(
-                       _("Upstream branch '%s' not stored as a remote-tracking branch"),
-                       upstream->merge[0]->src);
+               len = interpret_upstream_mark(name, namelen, at - name, buf);
+               if (len > 0)
+                       return len;
        }
-       free(cp);
-       cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
-       strbuf_reset(buf);
-       strbuf_addstr(buf, cp);
-       free(cp);
-       return len;
+ 
+       return -1;
  }
  
  int strbuf_branchname(struct strbuf *sb, const char *name)
@@@ -1302,7 -1333,7 +1331,7 @@@ static void diagnose_invalid_index_path
  
  static char *resolve_relative_path(const char *rel)
  {
 -      if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
 +      if (!starts_with(rel, "./") && !starts_with(rel, "../"))
                return NULL;
  
        if (!startup_info)