Make symbolize.cc thread safe even on shared fds #388
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ReadFromOffset in symbolize.cc used to call lseek() + read() to read data from fd. However, the fd may be reused for multiple symbolize requests from multiple threads, and causes a race around the fd read offset. This updates it to use pread() to resolve the race.
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JFYI @hajimehoshi |
ukai
reviewed
Nov 14, 2018
| SAFE_ASSERT(fd >= 0); | ||
| SAFE_ASSERT(count <= std::numeric_limits<ssize_t>::max()); | ||
| char *buf0 = reinterpret_cast<char *>(buf); | ||
| ssize_t num_bytes = 0; | ||
| while (num_bytes < count) { | ||
| ssize_t len; | ||
| NO_INTR(len = read(fd, buf0 + num_bytes, count - num_bytes)); | ||
| NO_INTR(len = pread(fd, buf0 + num_bytes, count - num_bytes, |
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Not sure, but IIUC, this is not used on Windows as we have defined(OS_WINDOWS) || defined(OS_CYGWIN) branch below.
durswd
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to durswd/glog
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Sep 2, 2019
Make symbolize.cc thread safe even on shared fds
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ReadFromOffset in symbolize.cc used to call lseek() + read() to read
data from fd. However, the fd may be reused for multiple symbolize
requests from multiple threads, and causes a race around the fd read
offset.
This updates it to use pread() to resolve the race.