[PATCH] Rework built-in diff to make its output more dense.

[git.git] / diff.c

diff --git a/diff.c b/diff.c
index c064e10..6511033 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -3,6 +3,7 @@
  */
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <signal.h>
 #include "cache.h"
 #include "diff.h"
 
@@ -81,35 +82,32 @@ static void builtin_diff(const char *name,
                         struct diff_tempfile *temp)
 {
        int i, next_at;
-       const char *diff_cmd = "diff -L'%s%s%s' -L'%s%s%s'";
+       const char *diff_cmd = "diff -L'%s%s' -L'%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);
        char *cmd;
        
-       /* diff_cmd and diff_arg have 8 %s in total which makes
-        * the sum of these strings 16 bytes larger than required.
+       /* diff_cmd and diff_arg have 6 %s in total which makes
+        * the sum of these strings 12 bytes larger than required.
         * we use 2 spaces around diff-opts, and we need to count
-        * terminating NUL, so we subtract 13 here.
+        * terminating NUL, so we subtract 9 here.
         */
        int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
-                       strlen(diff_arg) - 13);
+                       strlen(diff_arg) - 9);
        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]));
+                            strlen(input_name_sq[i]));
        }
 
        cmd = xmalloc(cmd_size);
@@ -117,13 +115,20 @@ static void builtin_diff(const char *name,
        next_at = 0;
        next_at += snprintf(cmd+next_at, cmd_size-next_at,
                            diff_cmd,
-                           path0[0], path1[0], mode[0],
-                           path0[1], path1[1], mode[1]);
+                           path0[0], path1[0], path0[1], path1[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, input_name_sq[0], input_name_sq[1]);
 
+       if (!path1[0][0])
+               printf("Created: %s (mode:%s)\n", name, temp[1].mode);
+       else if (!path1[1][0])
+               printf("Deleted: %s\n", name);
+       else if (strcmp(temp[0].mode, temp[1].mode))
+               printf("Mode changed: %s (%s->%s)\n", name,
+                      temp[0].mode, temp[1].mode);
+       fflush(NULL);
        execlp("/bin/sh","sh", "-c", cmd, NULL);
 }
 
@@ -135,6 +140,9 @@ 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, ".");
@@ -155,7 +163,7 @@ 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));
        }
@@ -196,6 +204,11 @@ 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 \
@@ -207,7 +220,8 @@ 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) {
@@ -219,6 +233,7 @@ void run_external_diff(const char *name,
                        atexit_asked = 1;
                        atexit(remove_tempfile);
                }
+               signal(SIGINT, remove_tempfile_on_signal);
        }
 
        fflush(NULL);
@@ -246,9 +261,17 @@ 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();
 }