http-push: add support for deleting remote branches

Processes new command-line arguments -d and -D to remove a remote branch
if the following conditions are met:
- one branch name is present on the command line
- the specified branch name matches exactly one remote branch name
- the remote HEAD is a symref
- the specified branch is not the remote HEAD
- the remote HEAD resolves to an object that exists locally (-d only)
- the specified branch resolves to an object that exists locally (-d only)
- the specified branch is an ancestor of the remote HEAD (-d only)

Signed-off-by: Nick Hengeveld <nickh@reactrix.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/http-push.c b/http-push.c
index 42b0d59..e44310f 100644 (file)
--- a/http-push.c
+++ b/http-push.c
@@ -7,6 +7,7 @@
 #include "http.h"
 #include "refs.h"
 #include "revision.h"
+#include "exec_cmd.h"
 
 #include <expat.h>
 
@@ -32,6 +33,7 @@ enum XML_Status {
 #define DAV_PROPFIND "PROPFIND"
 #define DAV_PUT "PUT"
 #define DAV_UNLOCK "UNLOCK"
+#define DAV_DELETE "DELETE"
 
 /* DAV lock flags */
 #define DAV_PROP_LOCKWR (1u << 0)
@@ -64,6 +66,9 @@ enum XML_Status {
 #define FETCHING (1u << 7)
 #define PUSHING  (1u << 8)
 
+/* We allow "recursive" symbolic refs. Only within reason, though */
+#define MAXDEPTH 5
+
 static int pushing = 0;
 static int aborted = 0;
 static char remote_dir_exists[256];
@@ -2103,6 +2108,197 @@ static int remote_exists(const char *path)
        return -1;
 }
 
+static void fetch_symref(char *path, char **symref, unsigned char *sha1)
+{
+       char *url;
+       struct buffer buffer;
+       struct active_request_slot *slot;
+       struct slot_results results;
+
+       url = xmalloc(strlen(remote->url) + strlen(path) + 1);
+       sprintf(url, "%s%s", remote->url, path);
+
+       buffer.size = 4096;
+       buffer.posn = 0;
+       buffer.buffer = xmalloc(buffer.size);
+
+       slot = get_active_slot();
+       slot->results = &results;
+       curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
+       curl_easy_setopt(slot->curl, CURLOPT_URL, url);
+       if (start_active_slot(slot)) {
+               run_active_slot(slot);
+               if (results.curl_result != CURLE_OK) {
+                       die("Couldn't get %s for remote symref\n%s",
+                           url, curl_errorstr);
+               }
+       } else {
+               die("Unable to start remote symref request");
+       }
+       free(url);
+
+       if (*symref != NULL)
+               free(*symref);
+       *symref = NULL;
+       memset(sha1, 0, 20);
+
+       if (buffer.posn == 0)
+               return;
+
+       /* If it's a symref, set the refname; otherwise try for a sha1 */
+       if (!strncmp((char *)buffer.buffer, "ref: ", 5)) {
+               *symref = xcalloc(buffer.posn - 5, 1);
+               strncpy(*symref, (char *)buffer.buffer + 5, buffer.posn - 6);
+       } else {
+               get_sha1_hex(buffer.buffer, sha1);
+       }
+
+       free(buffer.buffer);
+}
+
+static int verify_merge_base(unsigned char *head_sha1, unsigned char *branch_sha1)
+{
+       int pipe_fd[2];
+       pid_t merge_base_pid;
+       char line[PATH_MAX + 20];
+       unsigned char merge_sha1[20];
+       int verified = 0;
+
+       if (pipe(pipe_fd) < 0)
+               die("Verify merge base: pipe failed");
+
+       merge_base_pid = fork();
+       if (!merge_base_pid) {
+               static const char *args[] = {
+                       "merge-base",
+                       "-a",
+                       NULL,
+                       NULL,
+                       NULL
+               };
+               args[2] = strdup(sha1_to_hex(head_sha1));
+               args[3] = sha1_to_hex(branch_sha1);
+
+               dup2(pipe_fd[1], 1);
+               close(pipe_fd[0]);
+               close(pipe_fd[1]);
+               execv_git_cmd(args);
+               die("merge-base setup failed");
+       }
+       if (merge_base_pid < 0)
+               die("merge-base fork failed");
+
+       dup2(pipe_fd[0], 0);
+       close(pipe_fd[0]);
+       close(pipe_fd[1]);
+       while (fgets(line, sizeof(line), stdin) != NULL) {
+               if (get_sha1_hex(line, merge_sha1))
+                       die("expected sha1, got garbage:\n %s", line);
+               if (!memcmp(branch_sha1, merge_sha1, 20)) {
+                       verified = 1;
+                       break;
+               }
+       }
+
+       return verified;
+}
+
+static int delete_remote_branch(char *pattern, int force)
+{
+       struct ref *refs = remote_refs;
+       struct ref *remote_ref = NULL;
+       unsigned char head_sha1[20];
+       char *symref = NULL;
+       int match;
+       int patlen = strlen(pattern);
+       int i;
+       struct active_request_slot *slot;
+       struct slot_results results;
+       char *url;
+
+       /* Find the remote branch(es) matching the specified branch name */
+       for (match = 0; refs; refs = refs->next) {
+               char *name = refs->name;
+               int namelen = strlen(name);
+               if (namelen < patlen ||
+                   memcmp(name + namelen - patlen, pattern, patlen))
+                       continue;
+               if (namelen != patlen && name[namelen - patlen - 1] != '/')
+                       continue;
+               match++;
+               remote_ref = refs;
+       }
+       if (match == 0)
+               return error("No remote branch matches %s", pattern);
+       if (match != 1)
+               return error("More than one remote branch matches %s",
+                            pattern);
+
+       /*
+        * Remote HEAD must be a symref (not exactly foolproof; a remote
+        * symlink to a symref will look like a symref)
+        */
+       fetch_symref("HEAD", &symref, head_sha1);
+       if (!symref)
+               return error("Remote HEAD is not a symref");
+
+       /* Remote branch must not be the remote HEAD */
+       for (i=0; symref && i<MAXDEPTH; i++) {
+               if (!strcmp(remote_ref->name, symref))
+                       return error("Remote branch %s is the current HEAD",
+                                    remote_ref->name);
+               fetch_symref(symref, &symref, head_sha1);
+       }
+
+       /* Run extra sanity checks if delete is not forced */
+       if (!force) {
+               /* Remote HEAD must resolve to a known object */
+               if (symref)
+                       return error("Remote HEAD symrefs too deep");
+               if (is_zero_sha1(head_sha1))
+                       return error("Unable to resolve remote HEAD");
+               if (!has_sha1_file(head_sha1))
+                       return error("Remote HEAD resolves to object %s\nwhich does not exist locally, perhaps you need to fetch?", sha1_to_hex(head_sha1));
+
+               /* Remote branch must resolve to a known object */
+               if (is_zero_sha1(remote_ref->old_sha1))
+                       return error("Unable to resolve remote branch %s",
+                                    remote_ref->name);
+               if (!has_sha1_file(remote_ref->old_sha1))
+                       return error("Remote branch %s resolves to object %s\nwhich does not exist locally, perhaps you need to fetch?", remote_ref->name, sha1_to_hex(remote_ref->old_sha1));
+
+               /* Remote branch must be an ancestor of remote HEAD */
+               if (!verify_merge_base(head_sha1, remote_ref->old_sha1)) {
+                       return error("The branch '%s' is not a strict subset of your current HEAD.\nIf you are sure you want to delete it, run:\n\t'git http-push -D %s %s'", remote_ref->name, remote->url, pattern);
+               }
+       }
+
+       /* Send delete request */
+       fprintf(stderr, "Removing remote branch '%s'\n", remote_ref->name);
+       url = xmalloc(strlen(remote->url) + strlen(remote_ref->name) + 1);
+       sprintf(url, "%s%s", remote->url, remote_ref->name);
+       slot = get_active_slot();
+       slot->results = &results;
+       curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);
+       curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_null);
+       curl_easy_setopt(slot->curl, CURLOPT_URL, url);
+       curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, DAV_DELETE);
+       if (start_active_slot(slot)) {
+               run_active_slot(slot);
+               free(url);
+               if (results.curl_result != CURLE_OK)
+                       return error("DELETE request failed (%d/%ld)\n",
+                                    results.curl_result, results.http_code);
+       } else {
+               free(url);
+               return error("Unable to start DELETE request");
+       }
+
+       return 0;
+}
+
 int main(int argc, char **argv)
 {
        struct transfer_request *request;
@@ -2112,6 +2308,8 @@ int main(int argc, char **argv)
        struct remote_lock *ref_lock = NULL;
        struct remote_lock *info_ref_lock = NULL;
        struct rev_info revs;
+       int delete_branch = 0;
+       int force_delete = 0;
        int objects_to_send;
        int rc = 0;
        int i;
@@ -2138,7 +2336,15 @@ int main(int argc, char **argv)
                                push_verbosely = 1;
                                continue;
                        }
-                       usage(http_push_usage);
+                       if (!strcmp(arg, "-d")) {
+                               delete_branch = 1;
+                               continue;
+                       }
+                       if (!strcmp(arg, "-D")) {
+                               delete_branch = 1;
+                               force_delete = 1;
+                               continue;
+                       }
                }
                if (!remote->url) {
                        remote->url = arg;
@@ -2158,6 +2364,9 @@ int main(int argc, char **argv)
        if (!remote->url)
                usage(http_push_usage);
 
+       if (delete_branch && nr_refspec != 1)
+               die("You must specify only one branch name when deleting a remote branch");
+
        memset(remote_dir_exists, -1, 256);
 
        http_init();
@@ -2193,6 +2402,14 @@ int main(int argc, char **argv)
        fprintf(stderr, "Fetching remote heads...\n");
        get_dav_remote_heads();
 
+       /* Remove a remote branch if -d or -D was specified */
+       if (delete_branch) {
+               if (delete_remote_branch(refspec[0], force_delete) == -1)
+                       fprintf(stderr, "Unable to delete remote branch %s\n",
+                               refspec[0]);
+               goto cleanup;
+       }
+
        /* match them up */
        if (!remote_tail)
                remote_tail = &remote_refs;