[PATCH] git-fsck-cache: Gracefully handle non-commit IDs

[git.git] / diff.c

diff --git a/diff.c b/diff.c
index 7383489..8659e4b 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -3,10 +3,10 @@
  */
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <signal.h>
 #include "cache.h"
 #include "diff.h"
 
-static char *diff_cmd = "diff -L'k/%s' -L'l/%s'";
 static char *diff_opts = "-pu";
 
 static const char *external_diff(void)
@@ -23,14 +23,12 @@ static const char *external_diff(void)
         * alternative styles you can specify via environment
         * variables are:
         *
-        * GIT_DIFF_CMD="diff -L '%s' -L '%s'"
         * GIT_DIFF_OPTS="-c";
         */
        if (getenv("GIT_EXTERNAL_DIFF"))
                external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
 
        /* In case external diff fails... */
-       diff_cmd = getenv("GIT_DIFF_CMD") ? : diff_cmd;
        diff_opts = getenv("GIT_DIFF_OPTS") ? : diff_opts;
 
        done_preparing = 1;
@@ -83,31 +81,50 @@ static struct diff_tempfile {
 static void builtin_diff(const char *name,
                         struct diff_tempfile *temp)
 {
-       static char *diff_arg  = "'%s' '%s'";
-       const char *name_1_sq = sq_expand(temp[0].name);
-       const char *name_2_sq = sq_expand(temp[1].name);
+       int i, next_at;
+       const char *diff_cmd = "diff -L'%s%s%s' -L'%s%s%s'";
+       const char *diff_arg  = "'%s' '%s'";
+       const char *input_name_sq[2];
+       const char *path0[2];
+       const char *path1[2];
+       char mode[2][20];
        const char *name_sq = sq_expand(name);
-
-       /* diff_cmd and diff_arg have 4 %s in total which makes
-        * the sum of these strings 8 bytes larger than required.
+       char *cmd;
+       
+       /* diff_cmd and diff_arg have 8 %s in total which makes
+        * the sum of these strings 16 bytes larger than required.
         * we use 2 spaces around diff-opts, and we need to count
-        * terminating NUL, so we subtract 5 here.
+        * terminating NUL, so we subtract 13 here.
         */
-       int cmd_size = (strlen(diff_cmd) + 
-                       strlen(name_sq) * 2 +
-                       strlen(diff_opts) +
-                       strlen(diff_arg) +
-                       strlen(name_1_sq) + strlen(name_2_sq)
-                       - 5);
-       char *cmd = xmalloc(cmd_size);
-       int next_at = 0;
+       int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
+                       strlen(diff_arg) - 13);
+       for (i = 0; i < 2; i++) {
+               input_name_sq[i] = sq_expand(temp[i].name);
+               if (!strcmp(temp[i].name, "/dev/null")) {
+                       path0[i] = "/dev/null";
+                       path1[i] = "";
+                       mode[i][0] = 0;
+               } else {
+                       path0[i] = i ? "l/" : "k/";
+                       path1[i] = name_sq;
+                       sprintf(mode[i], "  (mode:%s)", temp[i].mode);
+               }
+               cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
+                            strlen(mode[i]) + strlen(input_name_sq[i]));
+       }
 
+       cmd = xmalloc(cmd_size);
+
+       next_at = 0;
        next_at += snprintf(cmd+next_at, cmd_size-next_at,
-                           diff_cmd, name_sq, name_sq);
+                           diff_cmd,
+                           path0[0], path1[0], mode[0],
+                           path0[1], path1[1], mode[1]);
        next_at += snprintf(cmd+next_at, cmd_size-next_at,
                            " %s ", diff_opts);
        next_at += snprintf(cmd+next_at, cmd_size-next_at,
-                           diff_arg, name_1_sq, name_2_sq);
+                           diff_arg, input_name_sq[0], input_name_sq[1]);
+
        execlp("/bin/sh","sh", "-c", cmd, NULL);
 }
 
@@ -119,6 +136,9 @@ static void prepare_temp_file(const char *name,
 
        if (!one->file_valid) {
        not_a_valid_file:
+               /* A '-' entry produces this for file-2, and
+                * a '+' entry produces this for file-1.
+                */
                temp->name = "/dev/null";
                strcpy(temp->hex, ".");
                strcpy(temp->mode, ".");
@@ -139,7 +159,7 @@ static void prepare_temp_file(const char *name,
                                goto not_a_valid_file;
                        die("stat(%s): %s", temp->name, strerror(errno));
                }
-               strcpy(temp->hex, ".");
+               strcpy(temp->hex, sha1_to_hex(null_sha1));
                sprintf(temp->mode, "%06o",
                        S_IFREG |ce_permissions(st.st_mode));
        }
@@ -180,6 +200,11 @@ static void remove_tempfile(void)
                }
 }
 
+static void remove_tempfile_on_signal(int signo)
+{
+       remove_tempfile();
+}
+
 /* An external diff command takes:
  *
  * diff-cmd name infile1 infile1-sha1 infile1-mode \
@@ -191,7 +216,8 @@ void run_external_diff(const char *name,
                       struct diff_spec *two)
 {
        struct diff_tempfile *temp = diff_temp;
-       int pid, status;
+       pid_t pid;
+       int status;
        static int atexit_asked = 0;
 
        if (one && two) {
@@ -203,6 +229,7 @@ void run_external_diff(const char *name,
                        atexit_asked = 1;
                        atexit(remove_tempfile);
                }
+               signal(SIGINT, remove_tempfile_on_signal);
        }
 
        fflush(NULL);
@@ -230,9 +257,17 @@ void run_external_diff(const char *name,
                        printf("* Unmerged path %s\n", name);
                exit(0);
        }
-       if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status))
-               die("diff program failed");
-
+       if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status)) {
+               /* We do not check the exit status because typically
+                * diff exits non-zero if files are different, and
+                * we are not interested in knowing that.  We *knew*
+                * they are different and that's why we ran diff
+                * in the first place!  However if it dies by a signal,
+                * we stop processing immediately.
+                */
+               remove_tempfile();
+               die("external diff died unexpectedly.\n");
+       }
        remove_tempfile();
 }
 
@@ -256,7 +291,6 @@ void diff_addremove(int addremove, unsigned mode,
        
        if (path) {
                strcpy(concatpath, base);
-               strcat(concatpath, "/");
                strcat(concatpath, path);
        }
        run_external_diff(path ? concatpath : base, one, two);
@@ -278,7 +312,6 @@ void diff_change(unsigned old_mode, unsigned new_mode,
 
        if (path) {
                strcpy(concatpath, base);
-               strcat(concatpath, "/");
                strcat(concatpath, path);
        }
        run_external_diff(path ? concatpath : base, &spec[0], &spec[1]);