util.h

   1 /*
   2  * Copyright (C) 2012-2020 all contributors <cmogstored-public@yhbt.net>
   3  * License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>
   4  */
   5
   6 /* stringify +s+ */
   7 #define MOG_STR(s) MOG_STR0(s)
   8 #define MOG_STR0(s) #s
   9
  10 /*
  11  * some systems define EWOULDBLOCK to a different value than EAGAIN,
  12  * but POSIX allows them to be identical.
  13  */
  14 #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
  15 #  define case_EAGAIN case EAGAIN: case EWOULDBLOCK
  16 #else
  17 #  define case_EAGAIN case EAGAIN
  18 #endif
  19
  20 /* free(3) causes compiler warnings on const, so we de-const here */
  21 static inline void mog_free(const void *ptr)
  22 {
  23         union { const void *in; void *out; } deconst = { .in = ptr };
  24
  25         free(deconst.out);
  26 }
  27
  28 #define PRESERVE_ERRNO(code) do { \
  29         int save_err = errno; \
  30         code; \
  31         errno = save_err; \
  32 } while (0)
  33
  34 # define CHECK(type, expect, expr) do { \
  35         type checkvar = (expr); \
  36         assert(checkvar==(expect)&& "BUG" && __FILE__ && __LINE__); \
  37         } while (0)
  38
  39 /* compiler should optimize this away */
  40 __attribute__((const)) static inline off_t off_t_max(void)
  41 {
  42         return (off_t)(sizeof(long) == sizeof(off_t) ? LONG_MAX : LLONG_MAX);
  43 }
  44
  45 #if defined(HAVE_IOCTL) && defined(FIONBIO)
  46 /*
  47  * FIONBIO * requires only one syscall for reliable operation rather than
  48  * two syscalls with fcntl() calls, so use it if possible.
  49  */
  50 static inline int mog_set_nonblocking(int fd, const bool value)
  51 {
  52         int flag = value ? 1 : 0;
  53
  54         return ioctl(fd, FIONBIO, &flag);
  55 }
  56 #else /* use gnulib */
  57 #include "nonblocking.h"
  58 #define mog_set_nonblocking(fd, value) set_nonblocking_flag((fd), (value))
  59 #endif
  60
  61 /*
  62  * the only FD_* flag that exists as of 2012 is FD_CLOEXEC, if new ones
  63  * ever get defined, we wouldn't be using them in the first place without
  64  * updating this code... (no way they'd be on by default).
  65  */
  66 static inline int mog_set_cloexec(int fd, const bool set) /* vfork-safe */
  67 {
  68         return fcntl(fd, F_SETFD, set ? FD_CLOEXEC : 0);
  69 }
  70
  71 static inline bool mog_pthread_create_retryable(const int err)
  72 {
  73         /*
  74          * older versions of glibc return ENOMEM instead of EAGAIN
  75          * ref: https://www.sourceware.org/bugzilla/show_bug.cgi?id=386
  76          * Remove the ENOMEM check by 2023 (unless other OSes have this
  77          * bug).
  78          */
  79         return (err == EAGAIN || err == ENOMEM);
  80 }