Mercurial > hg > nginx
view src/os/unix/ngx_errno.c @ 5356:acd51b0f6fd4
Disable symlinks: use O_PATH to open path components.
It was introduced in Linux 2.6.39, glibc 2.14 and allows to obtain
file descriptors without actually opening files. Thus made it possible
to traverse path with openat() syscalls without the need to have read
permissions for path components. It is effectively emulates O_SEARCH
which is missing on Linux.
O_PATH is used in combination with O_RDONLY. The last one is ignored
if O_PATH is used, but it allows nginx to not fail when it was built on
modern system (i.e. glibc 2.14+) and run with a kernel older than 2.6.39.
Then O_PATH is unknown to the kernel and ignored, while O_RDONLY is used.
Sadly, fstat() is not working with O_PATH descriptors till Linux 3.6.
As a workaround we fallback to fstatat() with the AT_EMPTY_PATH flag
that was introduced at the same time as O_PATH.
author | Valentin Bartenev <vbart@nginx.com> |
---|---|
date | Mon, 02 Sep 2013 08:07:59 +0400 |
parents | f1a0de6eb505 |
children | 8cc5b0365ee5 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> /* * The strerror() messages are copied because: * * 1) strerror() and strerror_r() functions are not Async-Signal-Safe, * therefore, they cannot be used in signal handlers; * * 2) a direct sys_errlist[] array may be used instead of these functions, * but Linux linker warns about its usage: * * warning: `sys_errlist' is deprecated; use `strerror' or `strerror_r' instead * warning: `sys_nerr' is deprecated; use `strerror' or `strerror_r' instead * * causing false bug reports. */ static ngx_str_t *ngx_sys_errlist; static ngx_str_t ngx_unknown_error = ngx_string("Unknown error"); u_char * ngx_strerror(ngx_err_t err, u_char *errstr, size_t size) { ngx_str_t *msg; msg = ((ngx_uint_t) err < NGX_SYS_NERR) ? &ngx_sys_errlist[err]: &ngx_unknown_error; size = ngx_min(size, msg->len); return ngx_cpymem(errstr, msg->data, size); } ngx_int_t ngx_strerror_init(void) { char *msg; u_char *p; size_t len; ngx_err_t err; /* * ngx_strerror() is not ready to work at this stage, therefore, * malloc() is used and possible errors are logged using strerror(). */ len = NGX_SYS_NERR * sizeof(ngx_str_t); ngx_sys_errlist = malloc(len); if (ngx_sys_errlist == NULL) { goto failed; } for (err = 0; err < NGX_SYS_NERR; err++) { msg = strerror(err); len = ngx_strlen(msg); p = malloc(len); if (p == NULL) { goto failed; } ngx_memcpy(p, msg, len); ngx_sys_errlist[err].len = len; ngx_sys_errlist[err].data = p; } return NGX_OK; failed: err = errno; ngx_log_stderr(0, "malloc(%uz) failed (%d: %s)", len, err, strerror(err)); return NGX_ERROR; }