patch: implement --dry-run

function                                             old     new   delta
static.patch_longopts                                  -     137    +137
patch_main                                          2053    2135     +82
fail_hunk                                            132     139      +7
finish_oldfile                                       119     124      +5
packed_usage                                       32807   32787     -20
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 3/1 up/down: 231/-20)           Total: 211 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 86 insertions, 43 deletions

diff --git a/editors/patch.c b/editors/patch.c
index a51b7a502..eca6bc5f6 100644
--- a/editors/patch.c
+++ b/editors/patch.c
@@ -15,7 +15,6 @@
  * -D define wrap #ifdef and #ifndef around changes
  * -o outfile output here instead of in place
  * -r rejectfile write rejected hunks to this file
- * --dry-run (regression!)
  *
  * -f force (no questions asked)
  * -F fuzz (number, default 2)
@@ -34,23 +33,15 @@
 //usage:#define patch_trivial_usage
 //usage:       "[OPTIONS] [ORIGFILE [PATCHFILE]]"
 //usage:#define patch_full_usage "\n\n"
-//usage:        IF_LONG_OPTS(
-//usage:       "        -p,--strip N            Strip N leading components from file names"
-//usage:     "\n        -i,--input DIFF         Read DIFF instead of stdin"
-//usage:     "\n        -R,--reverse            Reverse patch"
-//usage:     "\n        -N,--forward            Ignore already applied patches"
-/*usage:     "\n        --dry-run               Don't actually change files" - TODO */
-//usage:     "\n        -E,--remove-empty-files Remove output files if they become empty"
-//usage:        )
-//usage:        IF_NOT_LONG_OPTS(
 //usage:       "        -p N    Strip N leading components from file names"
 //usage:     "\n        -i DIFF Read DIFF instead of stdin"
 //usage:     "\n        -R      Reverse patch"
 //usage:     "\n        -N      Ignore already applied patches"
 //usage:     "\n        -E      Remove output files if they become empty"
+//usage:        IF_LONG_OPTS(
+//usage:     "\n        --dry-run       Don't actually change files"
 //usage:        )
 /* -u "interpret as unified diff" is supported but not documented: this info is not useful for --help */
-/* -x "debug" is supported but does nothing */
 //usage:
 //usage:#define patch_example_usage
 //usage:       "$ patch -p1 < example.diff\n"
@@ -58,6 +49,7 @@
 
 #include "libbb.h"
 
+#define PATCH_DEBUG  0
 
 // libbb candidate?
 
@@ -122,16 +114,18 @@ struct globals {
 } while (0)
 
 
-#define FLAG_STR "Rup:i:NEx"
+#define FLAG_STR "Rup:i:NEfg"
 /* FLAG_REVERSE must be == 1! Code uses this fact. */
-#define FLAG_REVERSE (1 << 0)
-#define FLAG_u       (1 << 1)
-#define FLAG_PATHLEN (1 << 2)
-#define FLAG_INPUT   (1 << 3)
-#define FLAG_IGNORE  (1 << 4)
-#define FLAG_RMEMPTY (1 << 5)
-/* Enable this bit and use -x for debug output: */
-#define FLAG_DEBUG   (0 << 6)
+#define FLAG_REVERSE  (1 << 0)
+#define FLAG_u        (1 << 1)
+#define FLAG_PATHLEN  (1 << 2)
+#define FLAG_INPUT    (1 << 3)
+#define FLAG_IGNORE   (1 << 4)
+#define FLAG_RMEMPTY  (1 << 5)
+#define FLAG_f_unused (1 << 6)
+#define FLAG_g_unused (1 << 7)
+#define FLAG_dry_run  ((1 << 8) * ENABLE_LONG_OPTS)
+
 
 // Dispose of a line of input, either by writing it out or discarding it.
 
@@ -140,8 +134,6 @@ struct globals {
 // state = 3: write whole line to fileout
 // state > 3: write line+1 to fileout when *line != state
 
-#define PATCH_DEBUG (option_mask32 & FLAG_DEBUG)
-
 static void do_line(void *data)
 {
         struct double_list *dlist = data;
@@ -168,12 +160,14 @@ static void finish_oldfile(void)
                 }
                 xclose(TT.fileout);
 
-                temp = xstrdup(TT.tempname);
-                temp[strlen(temp) - 6] = '\0';
-                rename(TT.tempname, temp);
-                free(temp);
+                if (!ENABLE_LONG_OPTS || TT.tempname[0]) { /* not --dry-run? */
+                        temp = xstrdup(TT.tempname);
+                        temp[strlen(temp) - 6] = '\0';
+                        rename(TT.tempname, temp);
+                        free(temp);
+                        free(TT.tempname);
+                }
 
-                free(TT.tempname);
                 TT.tempname = NULL;
         }
         TT.fileout = TT.filein = -1;
@@ -197,8 +191,10 @@ static void fail_hunk(void)
         // Abort the copy and delete the temporary file.
         close(TT.filein);
         close(TT.fileout);
-        unlink(TT.tempname);
-        free(TT.tempname);
+        if (!ENABLE_LONG_OPTS || TT.tempname[0]) { /* not --dry-run? */
+                unlink(TT.tempname);
+                free(TT.tempname);
+        }
         TT.tempname = NULL;
 
         TT.state = 0;
@@ -239,6 +235,7 @@ static int apply_one_hunk(void)
         plist = TT.current_hunk;
         buf = NULL;
         if (reverse ? TT.oldlen : TT.newlen) for (;;) {
+//FIXME: this performs 1-byte reads:
                 char *data = xmalloc_reads(TT.filein, NULL);
 
                 TT.linenum++;
@@ -369,9 +366,45 @@ int patch_main(int argc UNUSED_PARAM, char **argv)
         long oldlen = oldlen; /* for compiler */
         long newlen = newlen; /* for compiler */
 
+#if ENABLE_LONG_OPTS
+        static const char patch_longopts[] ALIGN1 =
+                "reverse\0"               No_argument       "R"
+                "unified\0"               No_argument       "u"
+                "strip\0"                 Required_argument "p"
+                "input\0"                 Required_argument "i"
+                "forward\0"               No_argument       "N"
+# if ENABLE_DESKTOP
+                "remove-empty-files\0"    No_argument       "E" /*ignored*/
+                /* "debug"                Required_argument "x" */
+# endif
+                /* "Assume user knows what [s]he is doing, do not ask any questions": */
+                "force\0"                 No_argument       "f" /*ignored*/
+# if ENABLE_DESKTOP
+                /* "Controls actions when a file is under RCS or SCCS control,
+                 * and does not exist or is read-only and matches the default version,
+                 * or when a file is under ClearCase control and does not exist..."
+                 * IOW: rather obscure option.
+                 * But Gentoo's portage does use -g0
+                 */
+                "get\0"                   Required_argument "g" /*ignored*/
+# endif
+                "dry-run\0"               No_argument       "\xfd"
+# if ENABLE_DESKTOP
+                "backup-if-mismatch\0"    No_argument       "\xfe" /*ignored*/
+                "no-backup-if-mismatch\0" No_argument       "\xff" /*ignored*/
+# endif
+                ;
+#endif
+
         INIT_TT();
 
+#if ENABLE_LONG_OPTS
+        opts = getopt32long(argv, FLAG_STR, patch_longopts, &opt_p, &opt_i);
+#else
         opts = getopt32(argv, FLAG_STR, &opt_p, &opt_i);
+#endif
+        //bb_error_msg_and_die("opts:%x", opts);
+
         argv += optind;
         reverse = opts & FLAG_REVERSE;
         TT.prefix = (opts & FLAG_PATHLEN) ? xatoi(opt_p) : 0; // can be negative!
@@ -517,10 +550,12 @@ int patch_main(int argc UNUSED_PARAM, char **argv)
                                         if (option_mask32 & FLAG_RMEMPTY) {
                                                 // If flag -E or --remove-empty-files is set
                                                 printf("removing %s\n", name);
-                                                xunlink(name);
+                                                if (!(opts & FLAG_dry_run))
+                                                        xunlink(name);
                                         } else {
                                                 printf("patching file %s\n", name);
-                                                xclose(xopen(name, O_WRONLY | O_TRUNC));
+                                                if (!(opts & FLAG_dry_run))
+                                                        xclose(xopen(name, O_WRONLY | O_TRUNC));
                                         }
                                 // If we've got a file to open, do so.
                                 } else if (!(option_mask32 & FLAG_PATHLEN) || i <= TT.prefix) {
@@ -529,24 +564,32 @@ int patch_main(int argc UNUSED_PARAM, char **argv)
                                         // If the old file was null, we're creating a new one.
                                         if (strcmp(oldname, "/dev/null") == 0 || !oldsum) {
                                                 printf("creating %s\n", name);
-                                                s = strrchr(name, '/');
-                                                if (s) {
-                                                        *s = 0;
-                                                        bb_make_directory(name, -1, FILEUTILS_RECUR);
-                                                        *s = '/';
+                                                if (!(opts & FLAG_dry_run)) {
+                                                        s = strrchr(name, '/');
+                                                        if (s) {
+                                                                *s = '\0';
+                                                                bb_make_directory(name, -1, FILEUTILS_RECUR);
+                                                                *s = '/';
+                                                        }
+                                                        TT.filein = xopen(name, O_CREAT|O_EXCL|O_RDWR);
+                                                } else {
+                                                        TT.filein = xopen("/dev/null", O_RDONLY);
                                                 }
-                                                TT.filein = xopen(name, O_CREAT|O_EXCL|O_RDWR);
                                         } else {
                                                 printf("patching file %s\n", name);
                                                 TT.filein = xopen(name, O_RDONLY);
                                         }
 
-                                        TT.tempname = xasprintf("%sXXXXXX", name);
-                                        TT.fileout = xmkstemp(TT.tempname);
-                                        // Set permissions of output file
-                                        fstat(TT.filein, &statbuf);
-                                        fchmod(TT.fileout, statbuf.st_mode);
-
+                                        if (!(opts & FLAG_dry_run)) {
+                                                TT.tempname = xasprintf("%sXXXXXX", name);
+                                                TT.fileout = xmkstemp(TT.tempname);
+                                                // Set permissions of output file
+                                                fstat(TT.filein, &statbuf);
+                                                fchmod(TT.fileout, statbuf.st_mode);
+                                        } else {
+                                                TT.tempname = (char*)"";
+                                                TT.fileout = xopen("/dev/null", O_WRONLY);
+                                        }
                                         TT.linenum = 0;
                                         TT.hunknum = 0;
                                 }