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meminfo-writer: ensure we do not write outside our buffer

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Reading the max size would cause a NUL to be written after
the buffer, while an error would cause one to be written
before it.
This commit is contained in:
Vincent Penquerc'h 2013-12-26 10:40:12 -05:00 committed by Marek Marczykowski-Górecki
parent 2758d2a1d3
commit e6c29bbae1
1 changed files with 17 additions and 3 deletions
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20
qmemman/meminfo-writer.c
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@ -163,17 +163,31 @@ int main(int argc, char **argv)
} }
if (argc == 3) { if (argc == 3) {
/* if not waiting for signal, fork after first info written to xenstore */ /* if not waiting for signal, fork after first info written to xenstore */
n = pread(fd, buf, sizeof(buf), 0); n = pread(fd, buf, sizeof(buf)-1, 0);
if (n < 0) {
perror("pread");
exit(1);
}
buf[n] = 0; buf[n] = 0;
meminfo_data = parse(buf); meminfo_data = parse(buf);
if (meminfo_data) if (meminfo_data)
send_to_qmemman(xs, meminfo_data); send_to_qmemman(xs, meminfo_data);
if (fork() > 0) n = fork();
if (n < 0) {
perror("fork");
exit(1);
}
if (n > 0)
exit(0); exit(0);
usleep(delay);
} }
for (;;) { for (;;) {
n = pread(fd, buf, sizeof(buf), 0); n = pread(fd, buf, sizeof(buf)-1, 0);
if (n < 0) {
perror("pread");
exit(1);
}
buf[n] = 0; buf[n] = 0;
meminfo_data = parse(buf); meminfo_data = parse(buf);
if (meminfo_data) if (meminfo_data)