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deps: V8: backport a4545db

Original commit message:

    FreeBSD update of process library mapping listing.

    Not best to rely on /proc presence basically when
    the linux compatibily layer is enabled so
    going through more programmatically.

    Change-Id: Ida4973f9da6dec6e9caa6e419f3612ec5ef95048
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1710664
    Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
    Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#65442}

PR-URL: #31127
Refs: v8/v8@a4545db
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
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devnexen authored and BridgeAR committed Dec 29, 2019
1 parent 4a54f30 commit ca235112ae8b09ffc27d80199fa4506c45fc1674
Showing with 42 additions and 34 deletions.
  1. +42 −34 deps/v8/src/base/platform/platform-freebsd.cc
@@ -13,10 +13,12 @@
#include <sys/time.h>
#include <sys/types.h>
#include <sys/ucontext.h>
#include <sys/user.h>

#include <sys/fcntl.h> // open
#include <sys/mman.h> // mmap & munmap
#include <sys/stat.h> // open
#include <sys/sysctl.h>
#include <unistd.h> // getpagesize
// If you don't have execinfo.h then you need devel/libexecinfo from ports.
#include <errno.h>
@@ -46,41 +48,47 @@ static unsigned StringToLong(char* buffer) {

std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
std::vector<SharedLibraryAddress> result;
static const int MAP_LENGTH = 1024;
int fd = open("/proc/self/maps", O_RDONLY);
if (fd < 0) return result;
while (true) {
char addr_buffer[11];
addr_buffer[0] = '0';
addr_buffer[1] = 'x';
addr_buffer[10] = 0;
ssize_t bytes_read = read(fd, addr_buffer + 2, 8);
if (bytes_read < 8) break;
unsigned start = StringToLong(addr_buffer);
bytes_read = read(fd, addr_buffer + 2, 1);
if (bytes_read < 1) break;
if (addr_buffer[2] != '-') break;
bytes_read = read(fd, addr_buffer + 2, 8);
if (bytes_read < 8) break;
unsigned end = StringToLong(addr_buffer);
char buffer[MAP_LENGTH];
bytes_read = -1;
do {
bytes_read++;
if (bytes_read >= MAP_LENGTH - 1) break;
bytes_read = read(fd, buffer + bytes_read, 1);
if (bytes_read < 1) break;
} while (buffer[bytes_read] != '\n');
buffer[bytes_read] = 0;
// Ignore mappings that are not executable.
if (buffer[3] != 'x') continue;
char* start_of_path = index(buffer, '/');
// There may be no filename in this line. Skip to next.
if (start_of_path == nullptr) continue;
buffer[bytes_read] = 0;
result.push_back(SharedLibraryAddress(start_of_path, start, end));
int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_VMMAP, getpid()};
size_t miblen = sizeof(mib) / sizeof(mib[0]);
size_t buffer_size;
if (sysctl(mib, miblen, nullptr, &buffer_size, nullptr, 0) == 0) {
// Overallocate the buffer by 1/3 to account for concurrent
// kinfo_vmentry change. 1/3 is an arbitrary constant that
// works in practice.
buffer_size = buffer_size * 4 / 3;
std::vector<char> buffer(buffer_size);
int ret = sysctl(mib, miblen, buffer.data(), &buffer_size, nullptr, 0);

if (ret == 0 || (ret == -1 && errno == ENOMEM)) {
char* start = buffer.data();
char* end = start + buffer_size;

while (start < end) {
struct kinfo_vmentry* map =
reinterpret_cast<struct kinfo_vmentry*>(start);
const size_t ssize = map->kve_structsize;
char* path = map->kve_path;

CHECK_NE(0, ssize);

if ((map->kve_protection & KVME_PROT_READ) != 0 &&
(map->kve_protection & KVME_PROT_EXEC) != 0 && path[0] != '\0') {
char* sep = strrchr(path, '/');
std::string lib_name;
if (sep != nullptr) {
lib_name = std::string(++sep);
} else {
lib_name = std::string(path);
}
result.push_back(SharedLibraryAddress(
lib_name, reinterpret_cast<uintptr_t>(map->kve_start),
reinterpret_cast<uintptr_t>(map->kve_end)));
}

start += ssize;
}
}
}
close(fd);
return result;
}

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