diff options
Diffstat (limited to 'Src/compat.c')
| -rw-r--r-- | Src/compat.c | 66 |
1 files changed, 40 insertions, 26 deletions
diff --git a/Src/compat.c b/Src/compat.c index 88ceac2c8..8cfb8a3a5 100644 --- a/Src/compat.c +++ b/Src/compat.c @@ -105,7 +105,23 @@ strerror(int errnum) #endif -#ifdef HAVE_PATHCONF +#if 0 +/* pathconf(_PC_PATH_MAX) is not currently useful to zsh. The value * + * returned varies depending on a number of factors, e.g. the amount * + * of memory available to the operating system at a given time; thus * + * it can't be used for buffer allocation, or even as an indication * + * of whether an attempt to use or create a given pathname may fail * + * at any future time. * + * * + * The call is also permitted to fail if the argument path is not an * + * existing directory, so even to make sense of that one must search * + * for a valid directory somewhere in the path and adjust. Even if * + * it succeeds, the return value is relative to the input directory, * + * and therefore potentially relative to the length of the shortest * + * path either to that directory or to our working directory. * + * * + * Finally, see the note below for glibc; detection of pathconf() is * + * not by itself an indication that it works reliably. */ /* The documentation for pathconf() says something like: * * The limit is returned, if one exists. If the system does * @@ -114,34 +130,24 @@ strerror(int errnum) * -1 is returned, and errno is set to reflect the nature of * * the error. * * * - * This is less useful than may be, as one must reset errno to 0 (or * + * System calls are not permitted to set errno to 0; but we must (or * * some other flag value) in order to determine that the resource is * * unlimited. What use is leaving errno unchanged? Instead, define * * a wrapper that resets errno to 0 and returns 0 for "the system * - * does not have a limit," so that -1 always means a real error. * - * * - * This is replaced by a macro from system.h if not HAVE_PATHCONF. * - * - * Note that the length of a relative path is compared without first * - * prepending the current directory, if pathconf() does not return * - * an error. This is for consistency with the macro and with older * - * zsh behavior; it may be problematic in the ENOENT/ENOTDIR cases. */ + * does not have a limit," so that -1 always means a real error. */ /**/ mod_export long zpathmax(char *dir) { +#ifdef HAVE_PATHCONF long pathmax; errno = 0; if ((pathmax = pathconf(dir, _PC_PATH_MAX)) >= 0) { - /* This code is redundant if pathconf works correctly, but * - * some versions of glibc pathconf return a hardwired value. */ - if (strlen(dir) < pathmax) - return pathmax; - else - errno = ENAMETOOLONG; - } else if (errno == ENOENT || errno == ENOTDIR) { + /* Some versions of glibc pathconf return a hardwired value! */ + return pathmax; + } else if (errno == EINVAL || errno == ENOENT || errno == ENOTDIR) { /* Work backward to find a directory, until we run out of path. */ char *tail = strrchr(dir, '/'); while (tail > dir && tail[-1] == '/') @@ -158,8 +164,9 @@ zpathmax(char *dir) pathmax = pathconf(".", _PC_PATH_MAX); } if (pathmax > 0) { - if (strlen(dir) < pathmax) - return pathmax; + long taillen = (tail ? strlen(tail) : (strlen(dir) + 1)); + if (taillen < pathmax) + return pathmax - taillen; else errno = ENAMETOOLONG; } @@ -168,12 +175,20 @@ zpathmax(char *dir) return -1; else return 0; /* pathmax should be considered unlimited */ -} +#else + long dirlen = strlen(dir); + + /* The following is wrong if dir is not an absolute path. */ + return ((long) ((dirlen >= PATH_MAX) ? + ((errno = ENAMETOOLONG), -1) : + ((errno = 0), PATH_MAX - dirlen))); #endif +} +#endif // 0 #ifdef HAVE_SYSCONF -/* This is replaced by a macro from system.h if not HAVE_PATHCONF. * - * 0 is returned if _SC_OPEN_MAX is unavailable * +/* This is replaced by a macro from system.h if not HAVE_SYSCONF. * + * 0 is returned by sysconf if _SC_OPEN_MAX is unavailable; * * -1 is returned on error * * * * Neither of these should happen, but resort to OPEN_MAX rather * @@ -183,10 +198,9 @@ zpathmax(char *dir) mod_export long zopenmax(void) { - long openmax; - - openmax = sysconf(_SC_OPEN_MAX); - if(openmax < 1) + long openmax = sysconf(_SC_OPEN_MAX); + + if (openmax < 1) return OPEN_MAX; else return openmax; |