Mercurial > hg > octave-lojdl > gnulib-hg
changeset 11895:3ef16b8c79cd
Avoid running into nonexistent system calls repeatedly.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Mon, 24 Aug 2009 02:18:15 +0200 |
| parents | 6b94c8deb683 |
| children | 5982a4bdef97 |
| files | ChangeLog lib/dup3.c lib/pipe2.c |
| diffstat | 3 files changed, 30 insertions(+), 6 deletions(-) [+] |
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--- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2009-08-23 Bruno Haible <bruno@clisp.org> + + * lib/dup3.c (dup3): Test only once whether the system actually exists. + * lib/pipe2.c (pipe2): Likewise. + Suggested by Eric Blake. + 2009-08-23 Bruno Haible <bruno@clisp.org> Tolerate declared but missing dup3 syscall.
--- a/lib/dup3.c +++ b/lib/dup3.c @@ -53,9 +53,18 @@ /* Try the system call first, if it exists. (We may be running with a glibc that has the function but with an older kernel that lacks it.) */ { - int result = dup3 (oldfd, newfd, flags); - if (!(result < 0 && errno == ENOSYS)) - return result; + /* Cache the information whether the system call really exists. */ + static int have_dup3_really; /* 0 = unknown, 1 = yes, -1 = no */ + if (have_dup3_really >= 0) + { + int result = dup3 (oldfd, newfd, flags); + if (!(result < 0 && errno == ENOSYS)) + { + have_dup3_really = 1; + return result; + } + have_dup3_really = -1; + } } #endif
--- a/lib/pipe2.c +++ b/lib/pipe2.c @@ -45,9 +45,18 @@ /* Try the system call first, if it exists. (We may be running with a glibc that has the function but with an older kernel that lacks it.) */ { - int result = pipe2 (fd, flags); - if (!(result < 0 && errno == ENOSYS)) - return result; + /* Cache the information whether the system call really exists. */ + static int have_pipe2_really; /* 0 = unknown, 1 = yes, -1 = no */ + if (have_pipe2_really >= 0) + { + int result = pipe2 (fd, flags); + if (!(result < 0 && errno == ENOSYS)) + { + have_pipe2_really = 1; + return result; + } + have_pipe2_really = -1; + } } #endif