merge-file.c

   1 #include "cache.h"
   2 #include "run-command.h"
   3 #include "xdiff-interface.h"
   4 #include "blob.h"
   5
   6 static void rm_temp_file(const char *filename)
   7 {
   8         unlink(filename);
   9         free((void *)filename);
  10 }
  11
  12 static const char *write_temp_file(mmfile_t *f)
  13 {
  14         int fd;
  15         const char *tmp = getenv("TMPDIR");
  16         char *filename;
  17
  18         if (!tmp)
  19                 tmp = "/tmp";
  20         filename = mkpath("%s/%s", tmp, "git-tmp-XXXXXX");
  21         fd = mkstemp(filename);
  22         if (fd < 0)
  23                 return NULL;
  24         filename = xstrdup(filename);
  25         if (f->size != xwrite(fd, f->ptr, f->size)) {
  26                 rm_temp_file(filename);
  27                 return NULL;
  28         }
  29         close(fd);
  30         return filename;
  31 }
  32
  33 static void *read_temp_file(const char *filename, unsigned long *size)
  34 {
  35         struct stat st;
  36         char *buf = NULL;
  37         int fd = open(filename, O_RDONLY);
  38         if (fd < 0)
  39                 return NULL;
  40         if (!fstat(fd, &st)) {
  41                 *size = st.st_size;
  42                 buf = xmalloc(st.st_size);
  43                 if (st.st_size != xread(fd, buf, st.st_size)) {
  44                         free(buf);
  45                         buf = NULL;
  46                 }
  47         }
  48         close(fd);
  49         return buf;
  50 }
  51
  52 static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
  53 {
  54         void *buf;
  55         unsigned long size;
  56         char type[20];
  57
  58         buf = read_sha1_file(obj->object.sha1, type, &size);
  59         if (!buf)
  60                 return -1;
  61         if (strcmp(type, blob_type))
  62                 return -1;
  63         f->ptr = buf;
  64         f->size = size;
  65         return 0;
  66 }
  67
  68 static void free_mmfile(mmfile_t *f)
  69 {
  70         free(f->ptr);
  71 }
  72
  73 static void *three_way_filemerge(mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
  74 {
  75         void *res;
  76         const char *t1, *t2, *t3;
  77
  78         t1 = write_temp_file(base);
  79         t2 = write_temp_file(our);
  80         t3 = write_temp_file(their);
  81         res = NULL;
  82         if (t1 && t2 && t3) {
  83                 int code = run_command("merge", t2, t1, t3, NULL);
  84                 if (!code || code == -1)
  85                         res = read_temp_file(t2, size);
  86         }
  87         rm_temp_file(t1);
  88         rm_temp_file(t2);
  89         rm_temp_file(t3);
  90         return res;
  91 }
  92
  93 static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
  94 {
  95         int i;
  96         mmfile_t *dst = priv_;
  97
  98         for (i = 0; i < nbuf; i++) {
  99                 memcpy(dst->ptr + dst->size, mb[i].ptr, mb[i].size);
 100                 dst->size += mb[i].size;
 101         }
 102         return 0;
 103 }
 104
 105 static int generate_common_file(mmfile_t *res, mmfile_t *f1, mmfile_t *f2)
 106 {
 107         unsigned long size = f1->size < f2->size ? f1->size : f2->size;
 108         void *ptr = xmalloc(size);
 109         xpparam_t xpp;
 110         xdemitconf_t xecfg;
 111         xdemitcb_t ecb;
 112
 113         xpp.flags = XDF_NEED_MINIMAL;
 114         xecfg.ctxlen = 3;
 115         xecfg.flags = XDL_EMIT_COMMON;
 116         ecb.outf = common_outf;
 117
 118         res->ptr = ptr;
 119         res->size = 0;
 120
 121         ecb.priv = res;
 122         return xdl_diff(f1, f2, &xpp, &xecfg, &ecb);
 123 }
 124
 125 void *merge_file(struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
 126 {
 127         void *res = NULL;
 128         mmfile_t f1, f2, common;
 129
 130         /*
 131          * Removed in either branch?
 132          *
 133          * NOTE! This depends on the caller having done the
 134          * proper warning about removing a file that got
 135          * modified in the other branch!
 136          */
 137         if (!our || !their) {
 138                 char type[20];
 139                 if (base)
 140                         return NULL;
 141                 if (!our)
 142                         our = their;
 143                 return read_sha1_file(our->object.sha1, type, size);
 144         }
 145
 146         if (fill_mmfile_blob(&f1, our) < 0)
 147                 goto out_no_mmfile;
 148         if (fill_mmfile_blob(&f2, their) < 0)
 149                 goto out_free_f1;
 150
 151         if (base) {
 152                 if (fill_mmfile_blob(&common, base) < 0)
 153                         goto out_free_f2_f1;
 154         } else {
 155                 if (generate_common_file(&common, &f1, &f2) < 0)
 156                         goto out_free_f2_f1;
 157         }
 158         res = three_way_filemerge(&common, &f1, &f2, size);
 159         free_mmfile(&common);
 160 out_free_f2_f1:
 161         free_mmfile(&f2);
 162 out_free_f1:
 163         free_mmfile(&f1);
 164 out_no_mmfile:
 165         return res;
 166 }