GNU bug report logs - #76197
[PROPOSED] gzip: drop support for the GZIP env var

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: bug-gzip <at> gnu.org
Cc: Paul Eggert <eggert <at> cs.ucla.edu>
Subject: [PROPOSED] gzip: drop support for the GZIP env var
Date: Mon, 10 Feb 2025 23:22:34 -0800

The GZIP environment variable is too hazardous.
* gzip.c (env, ENV_OPTION):
* tailor.h (OPTIONS_VAR):
* util.c (SEPARATOR, add_envopt):
Remove.  All uses removed.
* gzip.c (main): Ignore GZIP.
* tests/gzip-env: Test that GZIP is ignored.
---
 NEWS           |  6 ++++
 doc/gzip.texi  | 11 ++-----
 gzip.1         | 18 ++++--------
 gzip.c         | 79 +-------------------------------------------------
 gzip.h         |  1 -
 tailor.h       |  4 ---
 tests/gzip-env | 19 +++++-------
 util.c         | 60 --------------------------------------
 znew.in        |  2 +-
 9 files changed, 24 insertions(+), 176 deletions(-)

diff --git a/NEWS b/NEWS
index e348355..0c4a2fc 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,12 @@ GNU gzip NEWS                                    -*- outline -*-
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Changes in behavior
+
+  The GZIP environment variable, which was marked as obsolescent in
+  gzip 1.7 (2016) due to its hazards, has been removed.  You can use
+  an alias or script instead.
+
 ** Bug fixes
 
   'gzip -d' no longer omits the last partial output buffer when the
diff --git a/doc/gzip.texi b/doc/gzip.texi
index cc05b60..1bfca98 100644
--- a/doc/gzip.texi
+++ b/doc/gzip.texi
@@ -487,14 +487,9 @@ complement to @command{tar}, not as a replacement.
 @chapter Environment
 @cindex Environment
 
-The obsolescent environment variable @env{GZIP} can hold a set of
-default options for @command{gzip}.  These options are interpreted
-first and can be overwritten by explicit command line parameters.  As
-this can cause problems when using scripts, this feature is supported
-only for options that are reasonably likely to not cause too much
-harm, and @command{gzip} warns if it is used.  This feature will be
-removed in a future release of @command{gzip}.
-
+Although previous verions of @command{gzip} examined the environment
+variable @env{GZIP} for a set of default options,
+this feature has been removed because it caused problems when using scripts.
 You can use an alias or script instead.  For example, if
 @command{gzip} is in the directory @samp{/usr/bin} you can prepend
 @file{$HOME/bin} to your @env{PATH} and create an executable script
diff --git a/gzip.1 b/gzip.1
index 0efe399..4afa243 100644
--- a/gzip.1
+++ b/gzip.1
@@ -416,20 +416,12 @@ such as tar or zip.
 GNU tar supports the \-z option to invoke gzip transparently.
 gzip is designed as a complement to tar, not as a replacement.
 .SH "ENVIRONMENT"
-The obsolescent environment variable
-.B GZIP
-can hold a set of default options for
-.BR gzip .
-These options are interpreted first and can be overwritten by explicit
-command line parameters.
-As this can cause problems when using scripts,
-this feature is supported only for options that are
-reasonably likely to not cause too much harm, and
+Although previous versions of
 .B gzip
-warns if it is used.
-This feature will be removed in a future release of
-.BR gzip .
-.PP
+examined the environment variable
+.B GZIP
+for a set of default options, this feature has been removed
+because it caused problems when using scripts.
 You can use an alias or script instead.
 For example, if
 .B gzip
diff --git a/gzip.c b/gzip.c
index a33841a..1fe589b 100644
--- a/gzip.c
+++ b/gzip.c
@@ -182,7 +182,6 @@ static int foreground = 0;   /* set if program run in foreground */
 static int last_member;      /* set for .zip and .Z files */
 static int part_nb;          /* number of parts in .gz file */
        off_t ifile_size;      /* input file size, -1 for devices (debug only) */
-static char *env;            /* contents of GZIP env variable */
 static char const *z_suffix; /* default suffix (can be set with --suffix) */
 static size_t z_len;         /* strlen(z_suffix) */
 
@@ -249,10 +248,6 @@ enum
   PRESUME_INPUT_TTY_OPTION = CHAR_MAX + 1,
   RSYNCABLE_OPTION,
   SYNCHRONOUS_OPTION,
-
-  /* A value greater than all valid long options, used as a flag to
-     distinguish options derived from the GZIP environment variable.  */
-  ENV_OPTION
 };
 
 static char const shortopts[] = "ab:cdfhH?klLmMnNqrS:tvVZ123456789";
@@ -413,9 +408,6 @@ int main (int argc, char **argv)
 {
     int file_count;     /* number of files to process */
     size_t proglen;     /* length of program_name */
-    char **argv_copy;
-    int env_argc;
-    char **env_argv;
 
     EXPAND(argc, argv); /* wild card expansion if necessary */
 
@@ -426,11 +418,6 @@ int main (int argc, char **argv)
     if (4 < proglen && strequ (program_name + proglen - 4, ".exe"))
       program_name[proglen - 4] = '\0';
 
-    /* Add options in GZIP environment variable if there is one */
-    argv_copy = argv;
-    env = add_envopt (&env_argc, &argv_copy, OPTIONS_VAR);
-    env_argv = env ? argv_copy : NULL;
-
 #ifndef GNU_STANDARD
 # define GNU_STANDARD 1
 #endif
@@ -454,49 +441,8 @@ int main (int argc, char **argv)
     z_len = strlen(z_suffix);
 
     while (true) {
-        int optc;
         int longind = -1;
-
-        if (env_argv)
-          {
-            if (env_argv[optind] && strequ (env_argv[optind], "--"))
-              optc = ENV_OPTION + '-';
-            else
-              {
-                optc = getopt_long (env_argc, env_argv, shortopts, longopts,
-                                    &longind);
-                if (0 <= optc)
-                  optc += ENV_OPTION;
-                else
-                  {
-                    if (optind != env_argc)
-                      {
-                        fprintf (stderr,
-                                 ("%s: %s: non-option in "OPTIONS_VAR
-                                  " environment variable\n"),
-                                 program_name, env_argv[optind]);
-                        try_help ();
-                      }
-
-                    /* Wait until here before warning, so that GZIP='-q'
-                       doesn't warn.  */
-                    if (env_argc != 1 && !quiet)
-                      fprintf (stderr,
-                               ("%s: warning: "OPTIONS_VAR" environment variable"
-                                " is deprecated; use an alias or script\n"),
-                               program_name);
-
-                    /* Start processing ARGC and ARGV instead.  */
-                    free (env_argv);
-                    env_argv = NULL;
-                    optind = 1;
-                    longind = -1;
-                  }
-              }
-          }
-
-        if (!env_argv)
-          optc = getopt_long (argc, argv, shortopts, longopts, &longind);
+        int optc = getopt_long (argc, argv, shortopts, longopts, &longind);
         if (optc < 0)
           break;
 
@@ -532,15 +478,12 @@ int main (int argc, char **argv)
         case 'M': /* undocumented, may change later */
             no_time = 0; break;
         case 'n':
-        case 'n' + ENV_OPTION:
             no_name = no_time = 1; break;
         case 'N':
-        case 'N' + ENV_OPTION:
             no_name = no_time = 0; break;
         case PRESUME_INPUT_TTY_OPTION:
             presume_input_tty = true; break;
         case 'q':
-        case 'q' + ENV_OPTION:
             quiet = 1; verbose = 0; break;
         case 'r':
 #if NO_DIR
@@ -553,7 +496,6 @@ int main (int argc, char **argv)
             break;
 
         case RSYNCABLE_OPTION:
-        case RSYNCABLE_OPTION + ENV_OPTION:
             rsync = 1;
             break;
         case 'S':
@@ -575,7 +517,6 @@ int main (int argc, char **argv)
             test = decompress = to_stdout = 1;
             break;
         case 'v':
-        case 'v' + ENV_OPTION:
             verbose++; quiet = 0; break;
         case 'V':
             version (); finish_out (); break;
@@ -584,28 +525,12 @@ int main (int argc, char **argv)
                     program_name);
             try_help ();
             break;
-        case '1' + ENV_OPTION:  case '2' + ENV_OPTION:  case '3' + ENV_OPTION:
-        case '4' + ENV_OPTION:  case '5' + ENV_OPTION:  case '6' + ENV_OPTION:
-        case '7' + ENV_OPTION:  case '8' + ENV_OPTION:  case '9' + ENV_OPTION:
-            optc -= ENV_OPTION;
-            FALLTHROUGH;
         case '1':  case '2':  case '3':  case '4':
         case '5':  case '6':  case '7':  case '8':  case '9':
             level = optc - '0';
             break;
 
         default:
-            if (ENV_OPTION <= optc && optc != ENV_OPTION + '?')
-              {
-                /* Output a diagnostic, since getopt_long didn't.  */
-                fprintf (stderr, "%s: ", program_name);
-                if (longind < 0)
-                  fprintf (stderr, "-%c: ", optc - ENV_OPTION);
-                else
-                  fprintf (stderr, "--%s: ", longopts[longind].name);
-                fprintf (stderr, ("option not valid in "OPTIONS_VAR
-                                  " environment variable\n"));
-              }
             try_help ();
         }
     } /* loop on all arguments */
@@ -2042,8 +1967,6 @@ do_exit (int exitcode)
 
     if (in_exit) exit(exitcode);
     in_exit = 1;
-    free(env);
-    env  = NULL;
     FREE(inbuf);
     FREE(outbuf);
     FREE(d_buf);
diff --git a/gzip.h b/gzip.h
index 855a88b..66b504b 100644
--- a/gzip.h
+++ b/gzip.h
@@ -314,7 +314,6 @@ extern char *strlwr       (char *s);
 extern char *gzip_base_name (char *fname) _GL_ATTRIBUTE_PURE;
 extern int xunlink        (char *fname);
 extern void make_simple_name (char *name);
-extern char *add_envopt   (int *argcp, char ***argvp, char const *env);
 _Noreturn extern void gzip_error (char const *m);
 _Noreturn extern void xalloc_die (void);
 extern void warning       (char const *m);
diff --git a/tailor.h b/tailor.h
index c9147b1..095d7ce 100644
--- a/tailor.h
+++ b/tailor.h
@@ -163,10 +163,6 @@
 #  define casemap(c) (c)
 #endif
 
-#ifndef OPTIONS_VAR
-#  define OPTIONS_VAR "GZIP"
-#endif
-
 #ifndef Z_SUFFIX
 #  define Z_SUFFIX ".gz"
 #endif
diff --git a/tests/gzip-env b/tests/gzip-env
index b7382d9..2da5915 100755
--- a/tests/gzip-env
+++ b/tests/gzip-env
@@ -1,5 +1,5 @@
 #!/bin/sh
-# Test the obsolescent GZIP environment variable.
+# Test that gzip is unaffected by the GZIP environment variable.
 
 # Copyright 2015-2025 Free Software Foundation, Inc.
 
@@ -23,20 +23,17 @@ echo a >exp || framework_failure_
 gzip <exp >in || framework_failure_
 
 fail=0
-GZIP=-qv gzip -d <in >out 2>err || fail=1
-compare exp out || fail=1
 
-for badopt in -- -c --stdout -d --decompress -f --force -h --help -k --keep \
+for opt in -qv \
+  -- -c --stdout -d --decompress -f --force -h --help -k --keep \
   -l --list -L --license -r --recursive -Sxxx --suffix=xxx '--suffix xxx' \
-  -t --test -V --version
-do
-  GZIP=$badopt gzip -d <in >out 2>err && fail=1
-done
-
-for goodopt in -n --no-name -N --name -q --quiet -v --verbose \
+  -t --test -V --version \
+  -n --no-name -N --name -q --quiet -v --verbose \
   -1 --fast -2 -3 -4 -5 -6 -7 -8 -9 --best
 do
-  GZIP=$goodopt gzip -d <in >out 2>err || fail=1
+  GZIP=$opt gzip <exp >inopt 2>err || fail=1
+  compare in inopt || fail=1
+  GZIP=$opt gzip -d <in >out 2>err || fail=1
   compare exp out || fail=1
 done
 
diff --git a/util.c b/util.c
index e3eb739..c799ac1 100644
--- a/util.c
+++ b/util.c
@@ -291,66 +291,6 @@ make_simple_name (char *name)
 }
 #endif
 
-/* Convert the value of the environment variable ENVVAR_NAME
-   to a newly allocated argument vector, and set *ARGCP and *ARGVP
-   to the number of arguments and to the vector, respectively.
-   Make the new vector's zeroth element equal to the old **ARGVP.
-   Return a pointer to the newly allocated string storage.
-
-   If the vector would be empty, do not allocate storage,
-   do not set *ARGCP and *ARGVP, and return NULL.  */
-
-#define SEPARATOR	" \t"	/* separators in env variable */
-
-char *add_envopt(
-    int *argcp,          /* pointer to argc */
-    char ***argvp,       /* pointer to argv */
-    char const *envvar_name) /* name of environment variable */
-{
-    char *p;             /* running pointer through env variable */
-    char **oargv;        /* runs through old argv array */
-    char **nargv;        /* runs through new argv array */
-    int  nargc = 0;      /* number of arguments in env variable */
-    char *env_val;
-
-    env_val = getenv(envvar_name);
-    if (env_val == NULL) return NULL;
-
-    env_val = xstrdup (env_val);
-
-    for (p = env_val; *p; nargc++ ) {        /* move through env_val */
-        p += strspn(p, SEPARATOR);	     /* skip leading separators */
-        if (*p == '\0') break;
-
-        p += strcspn(p, SEPARATOR);	     /* find end of word */
-        if (*p) *p++ = '\0';		     /* mark it */
-    }
-    if (nargc == 0) {
-        free(env_val);
-        return NULL;
-    }
-    *argcp = nargc + 1;
-    /* Allocate the new argv array, with an extra element just in case
-     * the original arg list did not end with a NULL.
-     */
-    nargv = xcalloc (*argcp + 1, sizeof (char *));
-    oargv  = *argvp;
-    *argvp = nargv;
-
-    /* Copy the program name first */
-    *nargv++ = *oargv;
-
-    /* Then copy the environment args */
-    for (p = env_val; nargc > 0; nargc--) {
-        p += strspn(p, SEPARATOR);	     /* skip separators */
-        *(nargv++) = p;			     /* store start */
-        while (*p++) ;			     /* skip over word */
-    }
-
-    *nargv = NULL;
-    return env_val;
-}
-
 /* ========================================================================
  * Error handlers.
  */
diff --git a/znew.in b/znew.in
index b09d967..e9d87f3 100644
--- a/znew.in
+++ b/znew.in
@@ -55,7 +55,7 @@ new=0
 block=1024
 # block is the disk block size (best guess, need not be exact)
 
-# Beware -s or --suffix in $GZIP.
+# Beware -s or --suffix in $GZIP, used by gzip 1.13 and earlier.
 unset GZIP
 ext=.gz
 
-- 
2.45.2

Message #10 received at 76197 <at> debbugs.gnu.org (full text, mbox):

From: Lasse Collin <lasse.collin <at> tukaani.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 76197 <at> debbugs.gnu.org
Subject: Re: bug#76197: [PROPOSED] gzip: drop support for the GZIP env var
Date: Wed, 12 Feb 2025 15:58:05 +0200

On 2025-02-10 Paul Eggert wrote:
> The GZIP environment variable is too hazardous.

I looked at old mailing list threads to understand why the GZIP
environment variable was deprecated in the first place. The discussion
about deprecating the GZIP environment variable was a decade ago, so I
understand if commenting it now won't make a difference anymore. Take
this post as a final "are you sure" before you proceed, not as a start
of a new long discussion.

It seems that the story starts in grep where GREP_OPTIONS was creating
real-world problems.[1] GREP_OPTIONS was deprecated and then removed
completely. Trouble-free uses of GREP_OPTIONS were fairly limited
(perhaps --color=auto might have been such), so removing it seemed
reasonable. Specifically, it was unacceptable that many scripts would
need to unset GREP_OPTIONS.

In gzip, bug#20104 [2] refers to troubles caused by GREP_OPTIONS. The
thread doesn't mention or reference any real-world problems with GZIP
though. There are scripts that need to unset GZIP, but most scripts have
no reason to do that. I'm not saying that GZIP can never cause trouble,
I'm only saying it's less common than it was with GREP_OPTIONS.

gzip hasn't allowed arbitrary options in GZIP for years, which prevents
people from doing the silliest things. While it was a good change, I
suspect it didn't matter much in practice that --decompress or --suffix
were allowed in GZIP. If people do things that are *obviously* silly,
they can expect silly results.

Among reasonable use cases, one person had used GZIP to set the default
compression level.[3] GZIP=--synchronous could be a sensible use case
too but that option isn't allowed in GZIP.

For me, the use case for GZIP (and also TAR_OPTIONS) is injecting extra
options in specific situations without a need to modify any files. That
is, I don't keep those set all the time. Injecting options this way
is a bit hacky but it's convenient too. If something breaks in these
situations, it's obviously my own fault because I'm *effectively*
modifying the scripts that run gzip and tar.

The gzip manual suggests writing a wrapper script and putting it in
PATH. I'm not sure how it's an improvement:

  - Options are being injected to the gzip command line just like
    they are with the GZIP environment variable.

  - A few special scripts might know about the GZIP environment
    variable and be able to unset it. They are less likely to
    know that they should alter PATH to avoid extra gzip options.

I don't see security benefits in removing GZIP, but I wonder if I'm
missing something. As far as I understand, if an attacker can modify
arbitrary env vars, the situation is already bad. Some apps store
untrusted content in env vars but in those cases the names of the env
vars aren't under attacker's control. (In contrast, attacker controlled
filenames can become an attack vector if one extracts an untrusted
archive for examination, thus fixing CVE-2022-1271 in zgrep and xzgrep
mattered.)

zgrep, zdiff, and zcmp read the env vars GREP, DIFF, and CMP. These
allow injecting arbitrary commands (not just command line options).
zgrep's man page documents GREP. It's not marked as deprecated. It's
not very common to run zgrep or zdiff from other scripts, so *if* these
environment variables can cause problems, they won't occur as often as
they could with GZIP. To be clear, I think it's fine that these scripts
read those environment variables.

Several compression tools read command line options from environment
variables. At least in xz the feature was inspired by gzip.

  - pigz: GZIP, PIGZ
  - bzip2: BZIP2, BZIP
  - lzop: LZOP
  - xz: XZ_DEFAULTS, XZ_OPT
  - zip: ZIPOPT

zstd and lz4 read environment variables but don't parse them as command
line options.

While I have found GZIP convenient now and then, removing the feature
won't matter much to me personally. However, the removal makes gzip one
of the few compression tools that don't support setting even the
compression level via an environment variable.

[1] https://lists.gnu.org/archive/html/bug-grep/2014-05/msg00107.html
[2] https://lists.gnu.org/archive/html/bug-gzip/2015-03/msg00001.html
[3] https://lists.gnu.org/archive/html/bug-gzip/2017-02/msg00019.html

-- 
Lasse Collin

Message #15 received at 76197-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Lasse Collin <lasse.collin <at> tukaani.org>
Cc: 76197-done <at> debbugs.gnu.org
Subject: Re: bug#76197: [PROPOSED] gzip: drop support for the GZIP env var
Date: Wed, 19 Feb 2025 22:50:14 -0800

[Message part 1 (text/plain, inline)]

On 2025-02-12 05:58, Lasse Collin wrote:

> the removal makes gzip one
> of the few compression tools that don't support setting even the
> compression level via an environment variable.

Thanks for the review. On further thought I agree that, for backward 
compatibility reasons at least, the gzip command should continue to 
examine the GZIP environment variable for options like -9 that affect 
only performance (including compression performance). These options 
shouldn't cause the bigger glitches (and perhaps even security hazards) 
that behavior-oriented options can cause. This would be more in line 
with zstd, which takes this relatively-cautious approach to environment 
variables.

You mentioned --synchronous as being innocuous even though gzip 
currently doesn't allow it in GZIP, and that also is a good suggestion.

So I installed the attached patch instead into Savannah master gzip. It 
means gzip will pay attention to -1..-9, --rsyncable, and --synchronous 
but will silently ignore everything else in GZIP. The idea is that a 
garbage GZIP value shouldn't disrupt normal operations.

[0001-Ignore-GZIP-envvar-except-for-innocuous-flags.patch (text/x-patch, attachment)]

Message #18 received at 76197-done <at> debbugs.gnu.org (full text, mbox):

From: Lasse Collin <lasse.collin <at> tukaani.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 76197-done <at> debbugs.gnu.org
Subject: Re: bug#76197: [PROPOSED] gzip: drop support for the GZIP env var
Date: Sun, 23 Feb 2025 13:54:01 +0200

On 2025-02-19 Paul Eggert wrote:
> So I installed the attached patch instead into Savannah master gzip.
> It means gzip will pay attention to -1..-9, --rsyncable, and
> --synchronous

This sounds reasonable. It unambiguously prevents glitches in scripts.
For example, GZIP=-v may seem innocent but it affects --list output too
which some scripts parse. Also, -v undoes -q, and -q affects exit
status. There are safe use cases for GZIP=-v, but losing that feature
shouldn't be a major loss (it would hurt more if -v provided a
real-time progress indicator).

I wonder if -n (--no-name) should be allowed. GZIP=-9n was perhaps the
most common use case I had. It was with pipes, and nowadays -n is the
default for pipes anyway, so it doesn't matter for me.

Hypothetically, someone somewhere might rely on GZIP=-n when
compressing regular files. If -n is silently ignored, a script might
silently start producing .gz files with timestamps and filename
metadata. If someone is worried about that, they possibly have seen the
deprecation warning already and might have modified their script as
well, so the risk should be low. I don't have any examples of such use
cases, I'm just pondering what kind of tiny risks there could be.

Some script might expect the metadata to be stored, and GZIP=-n could
break it. I suspect such use cases are rare nowadays. Preserving the
filename was more important when OSes with short file names were still
in common use. Thus, I think the probability of negative surprises is
low if GZIP=-n is allowed. But I also understand that -n is an option
that affects more than just compression ratio, and that is the reason
why the commit dropped -n from GZIP. I don't have a clear opinion here.

> but will silently ignore everything else in GZIP. The idea is that a
> garbage GZIP value shouldn't disrupt normal operations.

I have mixed feelings about this. I understand that this way garbage in
GZIP cannot break scripts by making gzip fail. Also, if someone has
GZIP=-9n for pipe use, a silently-ignored -n will keep it working like
before, being compatible with both very old and current gzip versions.

On the other hand, it can be confusing that some options, that used to
work, no longer work for no apparent reason. One has to look at the
manual to figure it out. Typos won't be caught either.

How about printing a message to stderr if something is ignored in GZIP?
zstd and lz4 do that with their env vars. Even a vague message like "one
or more arguments in the GZIP environment variable were ignored" would
do if a more specific message is cumbersome to implement.

Such a message can break some special uses that check if something
was written to stderr, but those should be rare enough (they should
unset GZIP). After all, the current deprecation message about GZIP
usage was considered acceptable to add.

> These options shouldn't cause the bigger glitches (and perhaps even
> security hazards) that behavior-oriented options can cause.

I understand well that if everything was allowed in GZIP and someone
actually used that freedom in a wrong way, bad things could happen. What
I don't understand well is how big the risks are in practice. gzip and a
few other tools did or do suppport unrestricted options from env vars
for a long time. I haven't seen any security alerts about them, but that
doesn't mean that they don't or won't exist. I wouldn't add an
unrestricted env var to a new tool, but modifying existing tools always
has backward compatibility concerns.

I'm happy that the important functionality of GZIP is preserved. Thanks!

-- 
Lasse Collin

Message #21 received at 76197-done <at> debbugs.gnu.org (full text, mbox):

From: Antonio Diaz Diaz <antonio <at> gnu.org>
To: 76197-done <at> debbugs.gnu.org
Subject: Re: bug#76197: [PROPOSED] gzip: drop support for the GZIP env var
Date: Sun, 23 Feb 2025 18:01:39 +0100

Lasse Collin wrote:
> Hypothetically, someone somewhere might rely on GZIP=-n when
> compressing regular files.

Have you considered that removing GZIP, as Paul did originally, would 
maximize reliability, minimize maintenance work, prevent long discussions 
about what options GZIP should or should not allow, and not interfere with 
the user's freedom to define an environment variable for his/her own scripts:

  gzip ${MY_GZIP_OPT} [options] [files]


Best regards,
Antonio.

Message #24 received at 76197-done <at> debbugs.gnu.org (full text, mbox):

From: Lasse Collin <lasse.collin <at> tukaani.org>
To: Antonio Diaz Diaz <antonio <at> gnu.org>
Cc: 76197-done <at> debbugs.gnu.org
Subject: Re: bug#76197: [PROPOSED] gzip: drop support for the GZIP env var
Date: Mon, 3 Mar 2025 18:30:40 +0200

On 2025-02-23 Antonio Diaz Diaz wrote:
> Have you considered that removing GZIP, as Paul did originally, would 
> maximize reliability, minimize maintenance work,

I considered both pros and cons, including those pros you mentioned.
The cons are backward compatibility concerns and removal of a useful
feature (when used responsibly). I guess those cons don't matter to you,
but maintainers tend to consider such things especially when it's a
widely-used package.

For example, here is a Debian bug from 2020 about the GZIP deprecation
warning appearing in dgit:

    https://bugs-devel.debian.org/cgi-bin/bugreport.cgi?bug=975624

Previous the code used gzip in a pipe via tar. The fix for the
deprecation warning was to use a temporary file:

    https://salsa.debian.org/dgit-team/dgit/-/commit/710c9b49fff4001521dbb61c5df12156ae62f837

As you can see, the committer knew it made things worse, but it was a
quick way to fix the warning. Sometimes compromises are made; I'm not
criticizing the committer in any way. It's just an example where
changing an old and somewhat widely-used feature can have mildly
negative consequences *in practice* (this is an observation, not
critique). To be clear, I think restricting the options allowed in GZIP
was a positive change.

bug-gzip is a fairly quiet list, and small packages don't get much
feedback, so I thought it could be useful to express my thoughts. I
hope it was the right thing to do. Thanks!

-- 
Lasse Collin

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