Add strerrno(), and use it instead of its pattern #1375

alejandro-colomar · 2025-10-19T14:07:41Z

@ikerexxe , as you said you like this more than the addition of eprintf(), I've split these two patches from the other larger PR, so that this can be merged earlier.

Revisions:

v1b

Rebase

$ git rd 
1:  093ab3f0 = 1:  6a5f2898 lib/getdef.h: Add missing includes
2:  2f4eec2b ! 2:  c099a5f9 lib/string/: strerrno(): Add function
    @@ Commit message
     
      ## lib/Makefile.am ##
     @@ lib/Makefile.am: libshadow_la_SOURCES = \
    -   string/strdup/xstrdup.h \
    -   string/strdup/xstrndup.c \
    -   string/strdup/xstrndup.h \
    +   string/strdup/strndupa.h \
    +   string/strdup/strndup.c \
    +   string/strdup/strndup.h \
     +  string/strerrno.c \
     +  string/strerrno.h \
        string/strftime.c \
3:  ad1c40cf ! 3:  3519a8c7 lib/, src/: Use strerrno() instead of its pattern
    @@ lib/addgrps.c: add_groups(const char *list)
        }
      
     
    - ## lib/alloc/x/xcalloc.c ##
    -@@
    - 
    - #include "defines.h"
    - #include "shadowlog.h"
    -+#include "string/strerrno.h"
    - 
    - 
    - void *
    -@@ lib/alloc/x/xcalloc.c: xcalloc(size_t nmemb, size_t size)
    -   return p;
    - 
    - x:
    --  fprintf(log_get_logfd(), _("%s: %s\n"),
    --          log_get_progname(), strerror(errno));
    -+  fprintf(log_get_logfd(), _("%s: %s\n"), log_get_progname(), strerrno());
    -   exit(13);
    - }
    -
    - ## lib/alloc/x/xrealloc.c ##
    -@@
    - #include "alloc/reallocf.h"
    - #include "defines.h"
    - #include "shadowlog.h"
    -+#include "string/strerrno.h"
    - 
    - 
    - void *
    -@@ lib/alloc/x/xrealloc.c: xreallocarray(void *p, size_t nmemb, size_t size)
    -   return p;
    - 
    - x:
    --  fprintf(log_get_logfd(), _("%s: %s\n"),
    --          log_get_progname(), strerror(errno));
    -+  fprintf(log_get_logfd(), _("%s: %s\n"), log_get_progname(), strerrno());
    -   exit(13);
    - }
    -
      ## lib/commonio.c ##
     @@
      #include "string/sprintf/snprintf.h"
    @@ lib/commonio.c: static int do_lock_file (const char *file, const char *lock, boo
     
      ## lib/copydir.c ##
     @@
    - #include "string/sprintf/xaprintf.h"
    + #include "string/sprintf/aprintf.h"
      #include "string/strcmp/streq.h"
      #include "string/strcmp/strprefix.h"
     +#include "string/strerrno.h"
    @@ lib/copydir.c: static void error_acl (MAYBE_UNUSED struct error_context *ctx, co
      }
      
     
    + ## lib/exit_if_null.h ##
    +@@
    + 
    + #include "config.h"
    + 
    +-#include <errno.h>
    + #include <stddef.h>
    + #include <stdio.h>
    + #include <stdlib.h>
    +-#include <string.h>
    + 
    + #include "shadowlog.h"
    ++#include "string/strerrno.h"
    + 
    + 
    + /*
    +@@ lib/exit_if_null.h: inline void
    + exit_if_null_(void *p)
    + {
    +   if (p == NULL) {
    +-          fprintf(log_get_logfd(), "%s: %s\n",
    +-                  log_get_progname(), strerror(errno));
    ++          fprintf(log_get_logfd(), "%s: %s\n", log_get_progname(), strerrno());
    +           exit(13);
    +   }
    + }
    +
      ## lib/find_new_gid.c ##
     @@
      #include "groupio.h"
    @@ lib/idmapping.c: void write_mapping(int proc_dir_fd, int ranges, const struct ma
     
      ## lib/prefix_flag.c ##
     @@
    - #include "string/sprintf/xaprintf.h"
    + #include "string/sprintf/aprintf.h"
      #include "string/strcmp/streq.h"
      #include "string/strcmp/strprefix.h"
     +#include "string/strerrno.h"
    @@ lib/spawn.c: run_command(const char *cmd, const char *argv[],
        }
      
     
    - ## lib/string/strtok/xastrsep2ls.h ##
    -@@
    - #include "attr.h"
    - #include "shadowlog.h"
    - #include "string/strtok/astrsep2ls.h"
    -+#include "string/strerrno.h"
    - 
    - 
    - ATTR_ACCESS(read_write, 1) ATTR_ACCESS(write_only, 3)
    -@@ lib/string/strtok/xastrsep2ls.h: xastrsep2ls(char *s, const char *restrict delim, size_t *restrict np)
    - 
    -   return ls;
    - x:
    --  fprintf(log_get_logfd(), "%s: %s\n",
    --          log_get_progname(), strerror(errno));
    -+  fprintf(log_get_logfd(), "%s: %s\n", log_get_progname(), strerrno());
    -   exit(13);
    - }
    - 
    -
      ## lib/tcbfuncs.c ##
     @@
      #include "shadowlog_internal.h"
    @@ src/chage.c
     @@
      #include "string/strcmp/streq.h"
      #include "string/strcpy/strtcpy.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      #include "string/strftime.h"
      #include "time/day_to_str.h"
    @@ src/gpasswd.c
     @@
      #include "string/strcmp/streq.h"
      #include "string/strcpy/strtcpy.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
    ++
      
      struct option_flags {
        bool chroot;
    @@ src/login.c
     @@
      #include "string/strcmp/strprefix.h"
      #include "string/strcpy/strtcpy.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      #include "string/strftime.h"
      
    @@ src/newgrp.c
     @@
      #include "string/strcmp/streq.h"
      #include "string/strcmp/strprefix.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      
      #include <assert.h>
    @@ src/newusers.c
     @@
      #include "string/sprintf/snprintf.h"
      #include "string/strcmp/streq.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      #include "string/strtok/stpsep.h"
      #include "string/strtok/strsep2arr.h"
    @@ src/passwd.c
     @@
      #include "string/strcmp/strprefix.h"
      #include "string/strcpy/strtcpy.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      #include "time/day_to_str.h"
      
    @@ src/useradd.c
     @@
      #include "string/strcmp/streq.h"
      #include "string/strcmp/strprefix.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      #include "string/strtok/stpsep.h"
      
    @@ src/userdel.c
     @@
      #include "string/strcmp/streq.h"
      #include "string/strcmp/strprefix.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      
      
    @@ src/usermod.c
     @@
      #include "string/strcmp/streq.h"
      #include "string/strcmp/strprefix.h"
    - #include "string/strdup/xstrdup.h"
    + #include "string/strdup/strdup.h"
     +#include "string/strerrno.h"
      #include "time/day_to_str.h"
      #include "typetraits.h"
    @@ src/usermod.c: static void update_faillog (void)
     
      ## src/vipw.c ##
     @@
    + #include "string/sprintf/aprintf.h"
      #include "string/sprintf/snprintf.h"
    - #include "string/sprintf/xaprintf.h"
      #include "string/strcmp/streq.h"
     +#include "string/strerrno.h"

v1c

Add dependency in test_xaprintf. [@ikerexxe ]

$ git rd 
1:  6a5f28988 = 1:  6a5f28988 lib/getdef.h: Add missing includes
2:  c099a5f99 = 2:  c099a5f99 lib/string/: strerrno(): Add function
3:  3519a8c7b ! 3:  415166cfd lib/, src/: Use strerrno() instead of its pattern
    @@ src/vipw.c: vipwedit (const char *file, int (*file_lock) (void), int (*file_unlo
      #ifdef WITH_TCB
                if (tcb_mode) {
                        free(to_rename);
    +
    + ## tests/unit/Makefile.am ##
    +@@ tests/unit/Makefile.am: test_xaprintf_SOURCES = \
    +     ../../lib/shadowlog.c \
    +     ../../lib/string/sprintf/aprintf.c \
    +     ../../lib/string/strcmp/streq.c \
    ++    ../../lib/string/strerrno.c \
    +     test_xaprintf.c \
    +     $(NULL)
    + test_xaprintf_CFLAGS = \

v1d

Improve comment.

$ git rd 
1:  6a5f28988 = 1:  6a5f28988 lib/getdef.h: Add missing includes
2:  c099a5f99 ! 2:  bc8a1c4f6 lib/string/: strerrno(): Add function
    @@ lib/string/strerrno.h (new)
     +inline const char *strerrno(void);
     +
     +
    -+// string errno
    ++// strerrno - string errno
     +inline const char *
     +strerrno(void)
     +{
3:  415166cfd = 3:  29b03b500 lib/, src/: Use strerrno() instead of its pattern

v2

Use a macro instead of an inline function. This makes sure this doesn't create hidden dependencies between source files. Now we can remove the dependency in the unit tests for xaprintf().

I was using the inline function to const-ify the return value, as strerror(3) returns non-const (but can't be modified) which is dangerous. But we have const_cast(), which allows us to do the same in macros, so do that.

$ git rd 
1:  6a5f28988 = 1:  6a5f28988 lib/getdef.h: Add missing includes
2:  bc8a1c4f6 ! 2:  fbd2c3e37 lib/string/: strerrno(): Add function
    @@ Metadata
     Author: Alejandro Colomar <alx@kernel.org>
     
      ## Commit message ##
    -    lib/string/: strerrno(): Add function
    +    lib/string/: strerrno(): Add macro
     
         Signed-off-by: Alejandro Colomar <alx@kernel.org>
     
    @@ lib/string/strerrno.c (new)
     +#include "config.h"
     +
     +#include "string/strerrno.h"
    -+
    -+
    -+extern inline const char *strerrno(void);
     
      ## lib/string/strerrno.h (new) ##
     @@
    @@ lib/string/strerrno.h (new)
     +#include <errno.h>
     +#include <string.h>
     +
    -+
    -+inline const char *strerrno(void);
    ++#include "cast.h"
     +
     +
     +// strerrno - string errno
    -+inline const char *
    -+strerrno(void)
    -+{
    -+  return strerror(errno);
    -+}
    ++#define strerrno()  const_cast(const char *, strerror(errno))
     +
     +
     +#endif  // include guard
3:  29b03b500 ! 3:  bd24414b5 lib/, src/: Use strerrno() instead of its pattern
    @@ src/vipw.c: vipwedit (const char *file, int (*file_lock) (void), int (*file_unlo
      #ifdef WITH_TCB
                if (tcb_mode) {
                        free(to_rename);
    -
    - ## tests/unit/Makefile.am ##
    -@@ tests/unit/Makefile.am: test_xaprintf_SOURCES = \
    -     ../../lib/shadowlog.c \
    -     ../../lib/string/sprintf/aprintf.c \
    -     ../../lib/string/strcmp/streq.c \
    -+    ../../lib/string/strerrno.c \
    -     test_xaprintf.c \
    -     $(NULL)
    - test_xaprintf_CFLAGS = \

v3

Use a compound literal for the const conversion. This is safer than a cast, as it only accepts implicit conversions.

$ git rd
1:  6a5f28988 = 1:  6a5f28988 lib/getdef.h: Add missing includes
2:  fbd2c3e37 ! 2:  d846bbd90 lib/string/: strerrno(): Add macro
    @@ lib/string/strerrno.h (new)
     +
     +
     +// strerrno - string errno
    -+#define strerrno()  const_cast(const char *, strerror(errno))
    ++#define strerrno()  ((const char *){strerror(errno)})
     +
     +
     +#endif  // include guard
3:  bd24414b5 = 3:  d2962006e lib/, src/: Use strerrno() instead of its pattern

v3b

Remove unused include.

$ git rd 
1:  6a5f28988 = 1:  6a5f28988 lib/getdef.h: Add missing includes
2:  d846bbd90 ! 2:  01065f109 lib/string/: strerrno(): Add macro
    @@ lib/string/strerrno.h (new)
     +#include <errno.h>
     +#include <string.h>
     +
    -+#include "cast.h"
    -+
     +
     +// strerrno - string errno
     +#define strerrno()  ((const char *){strerror(errno)})
3:  d2962006e = 3:  619a2ff74 lib/, src/: Use strerrno() instead of its pattern

v4

Replace a few more cases.

$ git rd 
1:  6a5f28988 = 1:  6a5f28988 lib/getdef.h: Add missing includes
2:  01065f109 = 2:  01065f109 lib/string/: strerrno(): Add macro
3:  619a2ff74 ! 3:  785ca7b62 lib/, src/: Use strerrno() instead of its pattern
    @@ src/useradd.c: set_defaults(void)
                        goto err_free_new;
                }
        }
    +@@ src/useradd.c: set_defaults(void)
    +   assert(SNPRINTF(buf, "%s-", default_file) != -1);
    +   unlink (buf);
    +   if ((link (default_file, buf) != 0) && (ENOENT != errno)) {
    +-          int err = errno;
    +           fprintf (stderr,
    +                    _("%s: Cannot create backup file (%s): %s\n"),
    +-                   Prog, buf, strerror (err));
    ++                   Prog, buf, strerrno());
    +           unlink (new_file);
    +           goto err_free_def;
    +   }
    +@@ src/useradd.c: set_defaults(void)
    +    * Rename the new default file to its correct name.
    +    */
    +   if (rename (new_file, default_file) != 0) {
    +-          int err = errno;
    +           fprintf (stderr,
    +                    _("%s: rename: %s: %s\n"),
    +-                   Prog, new_file, strerror (err));
    ++                   Prog, new_file, strerrno());
    +           goto err_free_def;
    +   }
    + #ifdef WITH_AUDIT
     @@ src/useradd.c: static void faillog_reset (uid_t uid)
        if (-1 == fd) {
                fprintf (stderr,

Signed-off-by: Alejandro Colomar <alx@kernel.org>

ikerexxe

You need to update the unit test build configuration to include strerrno.c in the build for the test_xaprintf target, since that test uses exit_if_null.h which now depends on strerrno().

That should make CI green.

alejandro-colomar · 2025-11-03T10:53:42Z

You need to update the unit test build configuration to include strerrno.c in the build for the test_xaprintf target, since that test uses exit_if_null.h which now depends on strerrno().

That should make CI green.

Good eye. Thanks! :)

Signed-off-by: Alejandro Colomar <alx@kernel.org>

alejandro-colomar · 2025-11-03T11:34:16Z

CI is passing now, @ikerexxe .

Signed-off-by: Alejandro Colomar <alx@kernel.org>

ikerexxe

LGTM! Merging.

alejandro-colomar marked this pull request as ready for review October 19, 2025 14:07

alejandro-colomar requested review from hallyn and ikerexxe October 19, 2025 14:08

alejandro-colomar force-pushed the strerrno branch from 3eb6818 to ad1c40c Compare October 19, 2025 14:10

alejandro-colomar mentioned this pull request Oct 19, 2025

Add and use eprintf(), fprinte(), and eprinte() #1289

Draft

lib/getdef.h: Add missing includes

6a5f289

Signed-off-by: Alejandro Colomar <alx@kernel.org>

alejandro-colomar force-pushed the strerrno branch from ad1c40c to 3519a8c Compare October 27, 2025 14:13

ikerexxe reviewed Nov 3, 2025

View reviewed changes

alejandro-colomar force-pushed the strerrno branch from 3519a8c to 415166c Compare November 3, 2025 10:53

alejandro-colomar force-pushed the strerrno branch 3 times, most recently from bd24414 to d296200 Compare November 3, 2025 11:14

lib/string/: strerrno(): Add macro

01065f1

Signed-off-by: Alejandro Colomar <alx@kernel.org>

alejandro-colomar force-pushed the strerrno branch from d296200 to 619a2ff Compare November 3, 2025 11:17

alejandro-colomar mentioned this pull request Nov 3, 2025

Redefine SYSLOG() as a variadic macro #1379

Open

lib/, src/: Use strerrno() instead of its pattern

785ca7b

Signed-off-by: Alejandro Colomar <alx@kernel.org>

alejandro-colomar force-pushed the strerrno branch from 619a2ff to 785ca7b Compare November 3, 2025 16:36

ikerexxe approved these changes Nov 4, 2025

View reviewed changes

ikerexxe merged commit 90467ef into shadow-maint:master Nov 4, 2025
11 checks passed

alejandro-colomar deleted the strerrno branch November 4, 2025 11:55

alejandro-colomar self-assigned this Dec 27, 2025

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Add strerrno(), and use it instead of its pattern #1375

Add strerrno(), and use it instead of its pattern #1375

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alejandro-colomar commented Oct 19, 2025 •

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Add strerrno(), and use it instead of its pattern #1375

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