[PATCH] gzip: add "--keep" option to keep original files unchanged

[Rodrigo Campos]

By default it is disabled to keep everything working as before. And as a
shortcut "-K", instead of "-k", is used to avoid overlapping with pkzip
(although pkzip is not being used right now)

Also, this patch changes "--stdout" which "Write output on standard output; keep
original files unchanged" to imply "-K"
---
 gzip.1 |    9 ++++++---
 gzip.c |   11 ++++++++---
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/gzip.1 b/gzip.1
index c97aeb1..addd253 100644
--- a/gzip.1
+++ b/gzip.1
@@ -4,7 +4,7 @@ gzip, gunzip, zcat \- compress or expand files
 .SH SYNOPSIS
 .ll +8
 .B gzip
-.RB [ " \-acdfhlLnNrtvV19 " ]
+.RB [ " \-acdfhKlLnNrtvV19 " ]
 .RB [ \-S\ suffix ]
 [
 .I "name \&..."
@@ -12,7 +12,7 @@ gzip, gunzip, zcat \- compress or expand files
 .ll -8
 .br
 .B gunzip
-.RB [ " \-acfhlLnNrtvV " ]
+.RB [ " \-acfhKlLnNrtvV " ]
 .RB [ \-S\ suffix ]
 [
 .I "name \&..."
@@ -218,6 +218,9 @@ prompts to verify whether an existing file should be 
overwritten.
 .B \-h --help
 Display a help screen and quit.
 .TP
+.B \-K --keep
+Keep original files unchanged.
+.TP
 .B \-l --list
 For each compressed file, list the following fields:
 
@@ -392,7 +395,7 @@ Internet RFC 1951 (May 1996).
 Exit status is normally 0;
 if an error occurs, exit status is 1. If a warning occurs, exit status is 2.
 .TP
-Usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]
+Usage: gzip [-cdfhKlLnNrtvV19] [-S suffix] [file ...]
 Invalid options were specified on the command line.
 .TP
 \fIfile\fP\^: not in gzip format
diff --git a/gzip.c b/gzip.c
index 66529e0..b568c2c 100644
--- a/gzip.c
+++ b/gzip.c
@@ -167,6 +167,7 @@ static int ascii = 0;        /* convert end-of-lines to 
local OS conventions */
        int to_stdout = 0;    /* output to stdout (-c) */
 static int decompress = 0;   /* decompress (-d) */
 static int force = 0;        /* don't ask questions, compress links (-f) */
+static int keep = 0;         /* keep original files unchanged */
 static int no_name = -1;     /* don't save or restore the original file name */
 static int no_time = -1;     /* don't save or restore the original file time */
 static int recursive = 0;    /* recurse through directories (-r) */
@@ -256,6 +257,7 @@ static const struct option longopts[] =
     {"force",      0, 0, 'f'}, /* force overwrite of output file */
     {"help",       0, 0, 'h'}, /* give help */
  /* {"pkzip",      0, 0, 'k'},    force output in pkzip format */
+    {"keep",       0, 0, 'K'}, /* keep original files unchanged */
     {"list",       0, 0, 'l'}, /* list .gz file contents */
     {"license",    0, 0, 'L'}, /* display software license */
     {"no-name",    0, 0, 'n'}, /* don't save or restore original name & time */
@@ -334,6 +336,7 @@ local void help()
  "  -f, --force       force overwrite of output file and compress links",
  "  -h, --help        give this help",
 /*  -k, --pkzip       force output in pkzip format */
+ "  -K, --keep        keep original files unchanged",
  "  -l, --list        list compressed file contents",
  "  -L, --license     display software license",
 #ifdef UNDOCUMENTED
@@ -437,7 +440,7 @@ int main (int argc, char **argv)
     z_suffix = Z_SUFFIX;
     z_len = strlen(z_suffix);
 
-    while ((optc = getopt_long (argc, argv, "ab:cdfhH?lLmMnNqrS:tvVZ123456789",
+    while ((optc = getopt_long (argc, argv, 
"ab:cdfhH?KlLmMnNqrS:tvVZ123456789",
                                 longopts, (int *)0)) != -1) {
         switch (optc) {
         case 'a':
@@ -453,13 +456,15 @@ int main (int argc, char **argv)
                 }
             break;
         case 'c':
-            to_stdout = 1; break;
+            to_stdout = keep = 1; break;
         case 'd':
             decompress = 1; break;
         case 'f':
             force++; break;
         case 'h': case 'H':
             help(); do_exit(OK); break;
+        case 'K':
+            keep = 1; break;
         case 'l':
             list = decompress = to_stdout = 1; break;
         case 'L':
@@ -849,7 +854,7 @@ local void treat_file(iname)
     if (close (ifd) != 0)
       read_error ();
 
-    if (!to_stdout)
+    if (!keep)
       {
         sigset_t oldset;
         int unlink_errno;
-- 
1.7.10.4