strmove(): Add API, and use it instead of its pattern

[alejandro-colomar]

Cc: @kees, @uecker

---

Revisions:

v1b

• Rebase

$ git rd 
1:  cc0376415cbc = 1:  2969f95a3fdc lib/string/strcpy/: memmove_T(): Add API
2:  96c06d50e92c = 2:  fc6f018d2765 lib/string/strcpy/: strmove(): Add function
3:  28aeb9f6ae4d ! 3:  b1805c7f8806 src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern
    @@ src/usermod.c
      #include "string/strdup/strdup.h"
      #include "string/strerrno.h"
      #include "string/strspn/stprspn.h"
    -@@ src/usermod.c: static char *new_pw_passwd (char *pw_pass)
    +@@ src/usermod.c: new_pw_passwd(char *pw_pass, bool process_selinux)
                              "updating-password", user_newname, user_newid, 1);
      #endif
                SYSLOG ((LOG_INFO, "unlock user '%s' password", user_newname));

v2

• Don't use a statement expression unnecessarily.

$ git rd 
1:  2969f95a3fdc ! 1:  d038ef9e46eb lib/string/strcpy/: memmove_T(): Add API
    @@ lib/string/strcpy/memmove.h (new)
     +// memmove_T - memory move type-safe
     +#define memmove_T(dst, src, n, T)   memmove_T_(dst, src, n, typeas(T))
     +#define memmove_T_(dst, src, n, T)                                    \
    -+({                                                                    \
    -+  _Generic(dst, T *: (void)0);                                  \
    -+  _Generic(src, T *: (void)0);                                  \
    -+  (T *){memmove(dst, src, (n) * sizeof(T))};                    \
    -+})
    ++(                                                                     \
    ++  _Generic(dst, T *: (void)0),                                  \
    ++  _Generic(src, T *: (void)0),                                  \
    ++  (T *){memmove(dst, src, (n) * sizeof(T))}                     \
    ++)
     +
     +
     +#endif  // include guard
2:  fc6f018d2765 = 2:  05f665578fbd lib/string/strcpy/: strmove(): Add function
3:  b1805c7f8806 = 3:  5708a7e9e1d3 src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern

v2b

• Rebase

$ git rd 
1:  d038ef9e = 1:  64fda595 lib/string/strcpy/: memmove_T(): Add API
2:  05f66557 = 2:  c9830723 lib/string/strcpy/: strmove(): Add function
3:  5708a7e9 ! 3:  9bdb78a0 src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern
    @@ src/usermod.c
     @@ src/usermod.c: new_pw_passwd(char *pw_pass, bool process_selinux)
                              "updating-password", user_newname, user_newid, 1);
      #endif
    -           SYSLOG ((LOG_INFO, "unlock user '%s' password", user_newname));
    +           SYSLOG(LOG_INFO, "unlock user '%s' password", user_newname);
     -          memmove(pw_pass, pw_pass + 1, strlen(pw_pass));
     +          strmove(pw_pass, pw_pass + 1);
        } else if (pflg) {

v2c

• Rebase

$ git rd 
1:  64fda595ad05 ! 1:  f262f2d2f274 lib/string/strcpy/: memmove_T(): Add API
    @@ lib/string/README: strcpy/ - String copying
     +
      sprintf/ - Formatted string creation
      
    -     aprintf()
    +     aprintf(3)
     
      ## lib/string/strcpy/memmove.c (new) ##
     @@
2:  c98307235f8b = 2:  0542843b7a34 lib/string/strcpy/: strmove(): Add function
3:  9bdb78a02518 = 3:  9b6c18ce75cf src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern

v2d

• Rebase

$ git rd 
1:  f262f2d2f274 = 1:  cae69c557833 lib/string/strcpy/: memmove_T(): Add API
2:  0542843b7a34 = 2:  f4289243754c lib/string/strcpy/: strmove(): Add function
3:  9b6c18ce75cf ! 3:  e5c2238a5fa5 src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern
    @@ src/usermod.c
      #include "string/strcmp/strprefix.h"
     +#include "string/strcpy/strmove.h"
      #include "string/strdup/strdup.h"
    - #include "string/strerrno.h"
      #include "string/strspn/stprspn.h"
    + #include "sysconf.h"
     @@ src/usermod.c: new_pw_passwd(char *pw_pass, bool process_selinux)
                              "updating-password", user_newname, user_newid, 1);
      #endif

v2e

• Rebase

$ git rd 
1:  cae69c557833 = 1:  deaaad707d90 lib/string/strcpy/: memmove_T(): Add API
2:  f4289243754c = 2:  402e9eeb86cc lib/string/strcpy/: strmove(): Add function
3:  e5c2238a5fa5 = 3:  ff09b98f9a6f src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern

v3

• Use <memory.h> instead of <string.h>. Historically, and morally, it's more appropriate. It's quite portable, so it should be fine, even though it's non-standard. See memory.h(3head).

$ git rd 
1:  deaaad707d90 ! 1:  000b38d7d56e lib/string/strcpy/: memmove_T(): Add API
    @@ lib/string/strcpy/memmove.h (new)
     +
     +#include "config.h"
     +
    -+#include <string.h>
    ++#include <memory.h>
     +
     +#include "sizeof.h"
     +
2:  402e9eeb86cc = 2:  4b15b2b57c99 lib/string/strcpy/: strmove(): Add function
3:  ff09b98f9a6f = 3:  326a707b8eae src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern

v4

• Don't return a value from memmove_T(), since we don't need it.

$ git rd 
1:  000b38d7d56e ! 1:  3433e9779eab lib/string/strcpy/: memmove_T(): Add API
    @@ Commit message
         one, plus some offset, and thus will have the same const qualification
         (that is, it will not be qualified).
     
    +    Don't return anything, as we're not using the return value.  That avoids
    +    having to use a cast (we can't use a compound literal because of
    +    -Werror=unused-value).
    +
         Signed-off-by: Alejandro Colomar <alx@kernel.org>
     
      ## lib/Makefile.am ##
    @@ lib/string/strcpy/memmove.h (new)
     +
     +// memmove_T - memory move type-safe
     +#define memmove_T(dst, src, n, T)   memmove_T_(dst, src, n, typeas(T))
    -+#define memmove_T_(dst, src, n, T)                                    \
    -+(                                                                     \
    -+  _Generic(dst, T *: (void)0),                                  \
    -+  _Generic(src, T *: (void)0),                                  \
    -+  (T *){memmove(dst, src, (n) * sizeof(T))}                     \
    -+)
    ++#define memmove_T_(dst, src, n, T)  do                                \
    ++{                                                                     \
    ++  _Generic(dst, T *: (void)0);                                  \
    ++  _Generic(src, T *: (void)0);                                  \
    ++  memmove(dst, src, (n) * sizeof(T));                           \
    ++} while (0)
     +
     +
     +#endif  // include guard
2:  4b15b2b57c99 = 2:  cfbf55042e66 lib/string/strcpy/: strmove(): Add function
3:  326a707b8eae = 3:  970b7fd6d474 src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern

v4b

• Don't return anything from strmove() either.

$ git rd -U0
1:  3433e9779eab = 1:  3433e9779eab lib/string/strcpy/: memmove_T(): Add API
2:  cfbf55042e66 ! 2:  839e3a4737bf lib/string/strcpy/: strmove(): Add function
    @@ lib/string/strcpy/strmove.c (new)
    -+// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
    ++// SPDX-FileCopyrightText: 2025-2026, Alejandro Colomar <alx@kernel.org>
    @@ lib/string/strcpy/strmove.c (new)
    -+extern inline char *strmove(char *dst, char *src);
    ++extern inline void strmove(char *dst, char *src);
    @@ lib/string/strcpy/strmove.h (new)
    -+// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
    ++// SPDX-FileCopyrightText: 2025-2026, Alejandro Colomar <alx@kernel.org>
    @@ lib/string/strcpy/strmove.h (new)
    -+inline char *strmove(char *dst, char *src);
    ++inline void strmove(char *dst, char *src);
    @@ lib/string/strcpy/strmove.h (new)
    -+inline char *
    ++inline void
    @@ lib/string/strcpy/strmove.h (new)
    -+  return memmove_T(dst, src, strlen(src) + 1, char);
    ++  memmove_T(dst, src, strlen(src) + 1, char);
3:  970b7fd6d474 = 3:  7888284b548f src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern

v5

• Move memmove_T() to a new lib/memory/. [@ikerexxe ]

$ git rd --creation-factor=99
1:  3433e9779eab ! 1:  ad9bf2a0d7e9 lib/string/strcpy/: memmove_T(): Add API
    @@ Metadata
     Author: Alejandro Colomar <alx@kernel.org>
     
      ## Commit message ##
    -    lib/string/strcpy/: memmove_T(): Add API
    +    lib/memory/memcpy/: memmove_T(): Add API
     
         An interesting detail is that we require the second argument to be
         non-const, while the memmove(3) function gets a const void*.  This is
    @@ Commit message
     
      ## lib/Makefile.am ##
     @@ lib/Makefile.am: libshadow_la_SOURCES = \
    -   string/strcmp/strneq.h \
    -   string/strcmp/strprefix.c \
    -   string/strcmp/strprefix.h \
    -+  string/strcpy/memmove.c \
    -+  string/strcpy/memmove.h \
    -   string/strcpy/stpecpy.c \
    -   string/strcpy/stpecpy.h \
    -   string/strcpy/strncat.c \
    +   lockpw.c \
    +   loginprompt.c \
    +   mail.c \
    ++  memory/memcpy/memmove.c \
    ++  memory/memcpy/memmove.h \
    +   motd.c \
    +   myname.c \
    +   nss.c \
     
    - ## lib/string/README ##
    -@@ lib/string/README: strcpy/ - String copying
    -     MEMCPY()
    -   Like memcpy(3), but takes two arrays.
    - 
    -+    memmove_T()
    -+  Like memmove(3), but type safe.
    -+
    - sprintf/ - Formatted string creation
    - 
    -     aprintf(3)
    -
    - ## lib/string/strcpy/memmove.c (new) ##
    + ## lib/memory/memcpy/memmove.c (new) ##
     @@
    -+// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
    ++// SPDX-FileCopyrightText: 2025-2026, Alejandro Colomar <alx@kernel.org>
     +// SPDX-License-Identifier: BSD-3-Clause
     +
     +
     +#include "config.h"
     +
    -+#include "string/strcpy/memmove.h"
    ++#include "memory/memcpy/memmove.h"
     
    - ## lib/string/strcpy/memmove.h (new) ##
    + ## lib/memory/memcpy/memmove.h (new) ##
     @@
    -+// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
    ++// SPDX-FileCopyrightText: 2025-2026, Alejandro Colomar <alx@kernel.org>
     +// SPDX-License-Identifier: BSD-3-Clause
     +
     +
    -+#ifndef SHADOW_INCLUDE_LIB_STRING_STRCPY_MEMMOVE_H_
    -+#define SHADOW_INCLUDE_LIB_STRING_STRCPY_MEMMOVE_H_
    ++#ifndef SHADOW_INCLUDE_LIB_MEMORY_MEMCPY_MEMMOVE_H_
    ++#define SHADOW_INCLUDE_LIB_MEMORY_MEMCPY_MEMMOVE_H_
     +
     +
     +#include "config.h"
    @@ lib/string/strcpy/memmove.h (new)
     +
     +
     +#endif  // include guard
    +
    + ## lib/string/README ##
    +@@ lib/string/README: strcpy/ - String copying
    +     MEMCPY()
    +   Like memcpy(3), but takes two arrays.
    + 
    ++    memmove_T()
    ++  Like memmove(3), but type safe.
    ++
    + sprintf/ - Formatted string creation
    + 
    +     aprintf(3)
2:  839e3a4737bf ! 2:  7d370dcbf9eb lib/string/strcpy/: strmove(): Add function
    @@ Commit message
     
      ## lib/Makefile.am ##
     @@ lib/Makefile.am: libshadow_la_SOURCES = \
    -   string/strcpy/memmove.h \
    +   string/strcmp/strprefix.h \
        string/strcpy/stpecpy.c \
        string/strcpy/stpecpy.h \
     +  string/strcpy/strmove.c \
    @@ lib/string/strcpy/strmove.h (new)
     +#include <string.h>
     +
     +#include "attr.h"
    -+#include "string/strcpy/memmove.h"
    ++#include "memory/memcpy/memmove.h"
     +
     +
     +ATTR_STRING(2)
3:  7888284b548f = 3:  f32d45cd08e8 src/usermod.c: new_pw_passwd(): Use strmove() instead of its pattern