Add the ability to prefix something to the pathname to "checkout-cache.c"

This basically makes it trivial to use checkout-cache as a "export as
tree" function. Just read the desired tree into the index, and do a

	checkout-cache --prefix=export-dir/ -a

and checkout-cache will "export" the cache into the specified directory.

NOTE! The final "/" is important. The exported name is literally just
prefixed with the specified string, so you can also do something like

	checkout-cache --prefix=.merged- Makefile

to check out the currently cached copy of "Makefile" into the file
".merged-Makefile".

diff --git a/checkout-cache.c b/checkout-cache.c
index 5cd473c..972b1f7 100644 (file)
--- a/checkout-cache.c
+++ b/checkout-cache.c
@@ -32,6 +32,8 @@
  * of "-a" causing problems (not possible in the above example,
  * but get used to it in scripting!).
  */
+#include <sys/param.h>
+
 #include "cache.h"
 
 static int force = 0, quiet = 0;
@@ -65,7 +67,7 @@ static int create_file(const char *path, unsigned int mode)
        return fd;
 }
 
-static int write_entry(struct cache_entry *ce)
+static int write_entry(struct cache_entry *ce, const char *path)
 {
        int fd;
        void *new;
@@ -76,33 +78,38 @@ static int write_entry(struct cache_entry *ce)
        new = read_sha1_file(ce->sha1, type, &size);
        if (!new || strcmp(type, "blob")) {
                return error("checkout-cache: unable to read sha1 file of %s (%s)",
-                       ce->name, sha1_to_hex(ce->sha1));
+                       path, sha1_to_hex(ce->sha1));
        }
-       fd = create_file(ce->name, ntohl(ce->ce_mode));
+       fd = create_file(path, ntohl(ce->ce_mode));
        if (fd < 0) {
                free(new);
                return error("checkout-cache: unable to create %s (%s)",
-                       ce->name, strerror(errno));
+                       path, strerror(errno));
        }
        wrote = write(fd, new, size);
        close(fd);
        free(new);
        if (wrote != size)
-               return error("checkout-cache: unable to write %s", ce->name);
+               return error("checkout-cache: unable to write %s", path);
        return 0;
 }
 
-static int checkout_entry(struct cache_entry *ce)
+static int checkout_entry(struct cache_entry *ce, const char *base_dir)
 {
        struct stat st;
+       static char path[MAXPATHLEN+1];
+       int len = strlen(base_dir);
+
+       memcpy(path, base_dir, len);
+       strcpy(path + len, ce->name);
 
-       if (!stat(ce->name, &st)) {
+       if (!stat(path, &st)) {
                unsigned changed = cache_match_stat(ce, &st);
                if (!changed)
                        return 0;
                if (!force) {
                        if (!quiet)
-                               fprintf(stderr, "checkout-cache: %s already exists\n", ce->name);
+                               fprintf(stderr, "checkout-cache: %s already exists\n", path);
                        return 0;
                }
 
@@ -112,12 +119,12 @@ static int checkout_entry(struct cache_entry *ce)
                 * to emulate by hand - much easier to let the system
                 * just do the right thing)
                 */
-               unlink(ce->name);
+               unlink(path);
        }
-       return write_entry(ce);
+       return write_entry(ce, path);
 }
 
-static int checkout_file(const char *name)
+static int checkout_file(const char *name, const char *base_dir)
 {
        int pos = cache_name_pos(name, strlen(name));
        if (pos < 0) {
@@ -132,10 +139,10 @@ static int checkout_file(const char *name)
                }
                return -1;
        }
-       return checkout_entry(active_cache[pos]);
+       return checkout_entry(active_cache[pos], base_dir);
 }
 
-static int checkout_all(void)
+static int checkout_all(const char *base_dir)
 {
        int i;
 
@@ -143,7 +150,7 @@ static int checkout_all(void)
                struct cache_entry *ce = active_cache[i];
                if (ce_stage(ce))
                        continue;
-               if (checkout_entry(ce) < 0)
+               if (checkout_entry(ce, base_dir) < 0)
                        return -1;
        }
        return 0;
@@ -152,6 +159,7 @@ static int checkout_all(void)
 int main(int argc, char **argv)
 {
        int i, force_filename = 0;
+       const char *base_dir = "";
 
        if (read_cache() < 0) {
                die("invalid cache");
@@ -161,7 +169,7 @@ int main(int argc, char **argv)
                const char *arg = argv[i];
                if (!force_filename) {
                        if (!strcmp(arg, "-a")) {
-                               checkout_all();
+                               checkout_all(base_dir);
                                continue;
                        }
                        if (!strcmp(arg, "--")) {
@@ -176,8 +184,12 @@ int main(int argc, char **argv)
                                quiet = 1;
                                continue;
                        }
+                       if (!memcmp(arg, "--prefix=", 9)) {
+                               base_dir = arg+9;
+                               continue;
+                       }
                }
-               checkout_file(arg);
+               checkout_file(arg, base_dir);
        }
        return 0;
 }