documentation: add brief mention of cat-file to tutorial part I

diff --git a/mktag.c b/mktag.c
index 585677eb83cd0fd21963d21291a6af2b54fc9c84..f0fe5285b24d5a19c7d41b437a18a3851ae90802 100644 (file)
--- a/mktag.c
+++ b/mktag.c
@@ -1,4 +1,5 @@
 #include "cache.h"
+#include "tag.h"
 
 /*
  * A signature file has a very simple fixed format: three lines
@@ -44,42 +45,46 @@ static int verify_tag(char *buffer, unsigned long size)
        unsigned char sha1[20];
        const char *object, *type_line, *tag_line, *tagger_line;
 
-       if (size < 64 || size > MAXSIZE-1)
-               return -1;
+       if (size < 64)
+               return error("wanna fool me ? you obviously got the size wrong !\n");
+
        buffer[size] = 0;
 
        /* Verify object line */
        object = buffer;
        if (memcmp(object, "object ", 7))
-               return -1;
+               return error("char%d: does not start with \"object \"\n", 0);
+
        if (get_sha1_hex(object + 7, sha1))
-               return -1;
+               return error("char%d: could not get SHA1 hash\n", 7);
 
        /* Verify type line */
        type_line = object + 48;
        if (memcmp(type_line - 1, "\ntype ", 6))
-               return -1;
+               return error("char%d: could not find \"\\ntype \"\n", 47);
 
        /* Verify tag-line */
        tag_line = strchr(type_line, '\n');
        if (!tag_line)
-               return -1;
+               return error("char%td: could not find next \"\\n\"\n", type_line - buffer);
        tag_line++;
        if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
-               return -1;
+               return error("char%td: no \"tag \" found\n", tag_line - buffer);
 
        /* Get the actual type */
        typelen = tag_line - type_line - strlen("type \n");
        if (typelen >= sizeof(type))
-               return -1;
+               return error("char%td: type too long\n", type_line+5 - buffer);
+
        memcpy(type, type_line+5, typelen);
        type[typelen] = 0;
 
        /* Verify that the object matches */
        if (get_sha1_hex(object + 7, sha1))
-               return -1;
+               return error("char%d: could not get SHA1 hash but this is really odd since i got it before !\n", 7);
+
        if (verify_object(sha1, type))
-               return -1;
+               return error("char%d: could not verify object %s\n", 7, sha1);
 
        /* Verify the tag-name: we don't allow control characters or spaces in it */
        tag_line += 4;
@@ -89,14 +94,14 @@ static int verify_tag(char *buffer, unsigned long size)
                        break;
                if (c > ' ')
                        continue;
-               return -1;
+               return error("char%td: could not verify tag name\n", tag_line - buffer);
        }
 
        /* Verify the tagger line */
        tagger_line = tag_line;
 
        if (memcmp(tagger_line, "tagger", 6) || (tagger_line[6] == '\n'))
-               return -1;
+               return error("char%td: could not find \"tagger\"\n", tagger_line - buffer);
 
        /* The actual stuff afterwards we don't care about.. */
        return 0;
@@ -104,33 +109,29 @@ static int verify_tag(char *buffer, unsigned long size)
 
 int main(int argc, char **argv)
 {
-       unsigned long size;
-       char buffer[MAXSIZE];
+       unsigned long size = 4096;
+       char *buffer = malloc(size);
        unsigned char result_sha1[20];
 
        if (argc != 1)
                usage("cat <signaturefile> | git-mktag");
 
-       // Read the signature
-       size = 0;
-       for (;;) {
-               int ret = read(0, buffer + size, MAXSIZE - size);
-               if (!ret)
-                       break;
-               if (ret < 0) {
-                       if (errno == EAGAIN)
-                               continue;
-                       break;
-               }
-               size += ret;
+       setup_git_directory();
+
+       if (read_pipe(0, &buffer, &size)) {
+               free(buffer);
+               die("could not read from stdin");
        }
 
        // Verify it for some basic sanity: it needs to start with "object <sha1>\ntype\ntagger "
        if (verify_tag(buffer, size) < 0)
                die("invalid tag signature file");
 
-       if (write_sha1_file(buffer, size, "tag", result_sha1) < 0)
+       if (write_sha1_file(buffer, size, tag_type, result_sha1) < 0)
                die("unable to write tag file");
+
+       free(buffer);
+
        printf("%s\n", sha1_to_hex(result_sha1));
        return 0;
 }