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author | Rich Felker <dalias@aerifal.cx> | 2014-01-08 16:12:47 -0500 |
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committer | Rich Felker <dalias@aerifal.cx> | 2014-01-08 16:12:47 -0500 |
commit | 289294220f278a291452332da8f45cf756f57fe5 (patch) | |
tree | 289eae9f5bda95245159a8ce5e35fb328a0efe12 /src/ipc | |
parent | 131871a3d846369fd925d3f8edb692edbad77e4d (diff) | |
download | musl-289294220f278a291452332da8f45cf756f57fe5.tar.gz |
fix type of semctl variadic argument
per POSIX, the variadic argument has type union semun, which may
contain a pointer or int; the type read depends on the command being
issued. this allows the userspace part of the implementation to be
type-correct without requiring special-casing for different commands.
the kernel always expects to receive the argument interpreted as
unsigned long (or equivalently, a pointer), and does its own handling
of extracting the int portion from the representation, as needed.
this change fixes two possible issues: most immediately, reading the
argument as a (signed) long and passing it to the syscall would
perform incorrect sign-extension of pointers on the upcoming x32
target. the other possible issue is that some archs may use different
(user-space) argument-passing convention for unions, preventing va_arg
from correctly obtaining the argument when the type long (or even
unsigned long or void *) is passed to it.
Diffstat (limited to 'src/ipc')
-rw-r--r-- | src/ipc/semctl.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/src/ipc/semctl.c b/src/ipc/semctl.c index 274e2cf3..49927e2e 100644 --- a/src/ipc/semctl.c +++ b/src/ipc/semctl.c @@ -3,16 +3,22 @@ #include "syscall.h" #include "ipc.h" +struct semun { + int val; + struct semid_ds *buf; + unsigned short *array; +}; + int semctl(int id, int num, int cmd, ...) { - long arg; + struct semun arg; va_list ap; va_start(ap, cmd); - arg = va_arg(ap, long); + arg = va_arg(ap, struct semun); va_end(ap); #ifdef SYS_semctl - return syscall(SYS_semctl, id, num, cmd | IPC_64, arg); + return syscall(SYS_semctl, id, num, cmd | IPC_64, arg.buf); #else - return syscall(SYS_ipc, IPCOP_semctl, id, num, cmd | IPC_64, &arg); + return syscall(SYS_ipc, IPCOP_semctl, id, num, cmd | IPC_64, &arg.buf); #endif } |