diff options
Diffstat (limited to 'lib/idx.h')
| -rw-r--r-- | lib/idx.h | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/lib/idx.h b/lib/idx.h index 681c8c90f10..54ad5d81fe1 100644 --- a/lib/idx.h +++ b/lib/idx.h @@ -3,16 +3,16 @@ This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU General Public + modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either - version 3 of the License, or (at your option) any later version. + version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - General Public License for more details. + Lesser General Public License for more details. - You should have received a copy of the GNU General Public + You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ @@ -56,6 +56,26 @@ * Because 'size_t' is an unsigned type, and a signed type is better. See above. + Why not use 'ssize_t'? + + * 'ptrdiff_t' is more portable; it is standardized by ISO C + whereas 'ssize_t' is standardized only by POSIX. + + * 'ssize_t' is not required to be as wide as 'size_t', and some + now-obsolete POSIX platforms had 'size_t' wider than 'ssize_t'. + + * Conversely, some now-obsolete platforms had 'ptrdiff_t' wider + than 'size_t', which can be a win and conforms to POSIX. + + Won't this cause a problem with objects larger than PTRDIFF_MAX? + + * Typical modern or large platforms do not allocate such objects, + so this is not much of a problem in practice; for example, you + can safely write 'idx_t len = strlen (s);'. To port to older + small platforms where allocations larger than PTRDIFF_MAX could + in theory be a problem, you can use Gnulib's ialloc module, or + functions like ximalloc in Gnulib's xalloc module. + Why not use 'ptrdiff_t' directly? * Maintainability: When reading and modifying code, it helps to know that |