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ProcFS: Reads past the end of a generated file should be zero-length

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This commit is contained in:
Andreas Kling 2020-01-08 12:49:36 +01:00
parent 28ee5b0e98
commit fe1bf067b8
Notes: sideshowbarker 2024-07-19 10:16:16 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/fe1bf067b80
2 changed files with 27 additions and 7 deletions
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17
Kernel/FileSystem/ProcFS.cpp
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@ -1107,13 +1107,16 @@ ssize_t ProcFSInode::read_bytes(off_t offset, ssize_t count, u8* buffer, FileDes
}
auto& data = generated_data;
ssize_t nread = 0;
if (data.has_value()) {
nread = min(static_cast<off_t>(data.value().size() - offset), static_cast<off_t>(count));
memcpy(buffer, data.value().data() + offset, nread);
if (nread == 0 && description && description->generator_cache())
description->generator_cache().clear();
}
if (!data.has_value())
return 0;
if ((size_t)offset >= data.value().size())
return 0;
ssize_t nread = min(static_cast<off_t>(data.value().size() - offset), static_cast<off_t>(count));
memcpy(buffer, data.value().data() + offset, nread);
if (nread == 0 && description && description->generator_cache())
description->generator_cache().clear();
return nread;
}

17
Userland/test_io.cpp
View File

@ -140,6 +140,22 @@ void test_tmpfs_read_past_end()
close(fd);
}
void test_procfs_read_past_end()
{
int fd = open("/proc/uptime", O_RDONLY);
ASSERT(fd >= 0);
int rc = lseek(fd, 4096, SEEK_SET);
ASSERT(rc == 4096);
char buffer[16];
int nread = read(fd, buffer, sizeof(buffer));
if (nread != 0) {
fprintf(stderr, "Expected 0-length read past end of file in /proc\n");
}
close(fd);
}
int main(int, char**)
{
int rc;
@ -160,6 +176,7 @@ int main(int, char**)
test_ftruncate_negative();
test_mmap_directory();
test_tmpfs_read_past_end();
test_procfs_read_past_end();
return 0;
}