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upd: [ipc] posix shm shouldn't ftruncate when st_size > 0

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mutouyun 2022-10-30 17:04:35 +08:00
parent d15181fa49
commit bde06d7b0d
1 changed files with 29 additions and 13 deletions
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42
src/libipc/platform/posix/shm_impl.h
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@ -5,6 +5,7 @@
#pragma once
#include <string>
#include <memory> // std::unique_ptr
#include <cstddef>
#include <sys/stat.h>
@ -15,6 +16,7 @@
#include "libimp/log.h"
#include "libimp/system.h"
#include "libimp/detect_plat.h"
#include "libipc/shm.h"
@ -70,23 +72,38 @@ result<shm_t> shm_open(std::string name, std::size_t size, mode::type type) noex
log.error("shm_open fails. error = {}", sys::error());
return {};
}
LIBIMP_UNUSED auto guard = std::unique_ptr<int, void (*)(int *)>(&fd, [](int *pfd) {
if (pfd != nullptr) ::close(*pfd);
});
if (size == 0) {
/// @brief Try to get the size of this fd
struct stat st;
if (::fstat(fd, &st) == posix::failed) {
log.error("fstat fails. error = {}", sys::error());
::shm_unlink(name.c_str());
return {};
}
size = static_cast<std::size_t>(st.st_size);
/// @brief Truncate this fd to a specified length
} else if (::ftruncate(fd, size) != 0) {
log.error("ftruncate fails. error = {}", sys::error());
/// @brief Try to get the size of this fd
struct stat st;
if (::fstat(fd, &st) == posix::failed) {
log.error("fstat fails. error = {}", sys::error());
::shm_unlink(name.c_str());
return {};
}
/// @brief Truncate this fd to a specified length
auto ftruncate = [&log, &name](int fd, std::size_t size) {
if (::ftruncate(fd, size) != 0) {
log.error("ftruncate fails. error = {}", sys::error());
::shm_unlink(name.c_str());
return false;
}
return true;
};
if (size == 0) {
size = static_cast<std::size_t>(st.st_size);
if (!ftruncate(fd, size)) return {};
} else if (st.st_size > 0) {
/// @remark Based on the actual size.
size = static_cast<std::size_t>(st.st_size);
} else { // st.st_size <= 0
if (!ftruncate(fd, size)) return {};
}
/// @brief Creates a new mapping in the virtual address space of the calling process.
void *mem = ::mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (mem == MAP_FAILED) {
@ -94,7 +111,6 @@ result<shm_t> shm_open(std::string name, std::size_t size, mode::type type) noex
::shm_unlink(name.c_str());
return {};
}
::close(fd);
return new shm_handle{std::move(name), size, mem};
}