Mercurial > hg > nginx
view src/os/unix/ngx_errno.c @ 8018:5119c8150478
Fixed runtime handling of systems without EPOLLRDHUP support.
In 7583:efd71d49bde0 (nginx 1.17.5) along with introduction of the
ioctl(FIONREAD) support proper handling of systems without EPOLLRDHUP
support in the kernel (but with EPOLLRDHUP in headers) was broken.
Before the change, rev->available was never set to 0 unless
ngx_use_epoll_rdhup was also set (that is, runtime test for EPOLLRDHUP
introduced in 6536:f7849bfb6d21 succeeded). After the change,
rev->available might reach 0 on systems without runtime EPOLLRDHUP
support, stopping further reading in ngx_readv_chain() and ngx_unix_recv().
And, if EOF happened to be already reported along with the last event,
it is not reported again by epoll_wait(), leading to connection hangs
and timeouts on such systems.
This affects Linux kernels before 2.6.17 if nginx was compiled
with newer headers, and, more importantly, emulation layers, such as
DigitalOcean's App Platform's / gVisor's epoll emulation layer.
Fix is to explicitly check ngx_use_epoll_rdhup before the corresponding
rev->pending_eof tests in ngx_readv_chain() and ngx_unix_recv().
author | Marcus Ball <marcus.ball@live.com> |
---|---|
date | Mon, 30 May 2022 02:38:07 +0300 |
parents | c43a2e8fdf7e |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> static ngx_str_t ngx_unknown_error = ngx_string("Unknown error"); #if (NGX_HAVE_STRERRORDESC_NP) /* * The strerrordesc_np() function, introduced in glibc 2.32, is * async-signal-safe. This makes it possible to use it directly, * without copying error messages. */ u_char * ngx_strerror(ngx_err_t err, u_char *errstr, size_t size) { size_t len; const char *msg; msg = strerrordesc_np(err); if (msg == NULL) { msg = (char *) ngx_unknown_error.data; len = ngx_unknown_error.len; } else { len = ngx_strlen(msg); } size = ngx_min(size, len); return ngx_cpymem(errstr, msg, size); } ngx_int_t ngx_strerror_init(void) { return NGX_OK; } #else /* * 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_err_t ngx_first_error; static ngx_err_t ngx_last_error; u_char * ngx_strerror(ngx_err_t err, u_char *errstr, size_t size) { ngx_str_t *msg; if (err >= ngx_first_error && err < ngx_last_error) { msg = &ngx_sys_errlist[err - ngx_first_error]; } else { msg = &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; #if (NGX_SYS_NERR) ngx_first_error = 0; ngx_last_error = NGX_SYS_NERR; #elif (EPERM > 1000 && EPERM < 0x7fffffff - 1000) /* * If number of errors is not known, and EPERM error code has large * but reasonable value, guess possible error codes based on the error * messages returned by strerror(), starting from EPERM. Notably, * this covers GNU/Hurd, where errors start at 0x40000001. */ for (err = EPERM; err > EPERM - 1000; err--) { ngx_set_errno(0); msg = strerror(err); if (errno == EINVAL || msg == NULL || strncmp(msg, "Unknown error", 13) == 0) { continue; } ngx_first_error = err; } for (err = EPERM; err < EPERM + 1000; err++) { ngx_set_errno(0); msg = strerror(err); if (errno == EINVAL || msg == NULL || strncmp(msg, "Unknown error", 13) == 0) { continue; } ngx_last_error = err + 1; } #else /* * If number of errors is not known, guess it based on the error * messages returned by strerror(). */ ngx_first_error = 0; for (err = 0; err < 1000; err++) { ngx_set_errno(0); msg = strerror(err); if (errno == EINVAL || msg == NULL || strncmp(msg, "Unknown error", 13) == 0) { continue; } ngx_last_error = err + 1; } #endif /* * ngx_strerror() is not ready to work at this stage, therefore, * malloc() is used and possible errors are logged using strerror(). */ len = (ngx_last_error - ngx_first_error) * sizeof(ngx_str_t); ngx_sys_errlist = malloc(len); if (ngx_sys_errlist == NULL) { goto failed; } for (err = ngx_first_error; err < ngx_last_error; err++) { msg = strerror(err); if (msg == NULL) { ngx_sys_errlist[err - ngx_first_error] = ngx_unknown_error; continue; } len = ngx_strlen(msg); p = malloc(len); if (p == NULL) { goto failed; } ngx_memcpy(p, msg, len); ngx_sys_errlist[err - ngx_first_error].len = len; ngx_sys_errlist[err - ngx_first_error].data = p; } return NGX_OK; failed: err = errno; ngx_log_stderr(0, "malloc(%uz) failed (%d: %s)", len, err, strerror(err)); return NGX_ERROR; } #endif