Improve code readability by avoiding assignments inside if()

[strace] / signal.c

diff --git a/signal.c b/signal.c
index 889134ad57d1a48bb8ad8698bbe7d43a0ec107ea..b623ac8dcbfa3bb257a5ff7338174710308cd6ec 100644 (file)
--- a/signal.c
+++ b/signal.c
@@ -144,28 +144,6 @@ struct sigcontext
 
 #endif /* LINUX */
 
-const char *const signalent0[] = {
-#include "signalent.h"
-};
-const int nsignals0 = ARRAY_SIZE(signalent0);
-
-#if SUPPORTED_PERSONALITIES >= 2
-const char *const signalent1[] = {
-#include "signalent1.h"
-};
-const int nsignals1 = ARRAY_SIZE(signalent1);
-#endif /* SUPPORTED_PERSONALITIES >= 2 */
-
-#if SUPPORTED_PERSONALITIES >= 3
-const char *const signalent2[] = {
-#include "signalent2.h"
-};
-const int nsignals2 = ARRAY_SIZE(signalent2);
-#endif /* SUPPORTED_PERSONALITIES >= 3 */
-
-const char *const *signalent;
-int nsignals;
-
 #if defined(SUNOS4) || defined(FREEBSD)
 
 static const struct xlat sigvec_flags[] = {
@@ -262,6 +240,28 @@ static const struct xlat sigprocmaskcmds[] = {
 #endif
 #endif
 
+/* Note on the size of sigset_t:
+ *
+ * In glibc, sigset_t is an array with space for 1024 bits (!),
+ * even though all arches supported by Linux have only 64 signals
+ * except MIPS, which has 128. IOW, it is 128 bytes long.
+ *
+ * In-kernel sigset_t is sized correctly (it is either 64 or 128 bit long).
+ * However, some old syscall return only 32 lower bits (one word).
+ * Example: sys_sigpending vs sys_rt_sigpending.
+ *
+ * Be aware of this fact when you try to
+ *     memcpy(&tcp->u_arg[1], &something, sizeof(sigset_t))
+ * - sizeof(sigset_t) is much bigger than you think,
+ * it may overflow tcp->u_arg[] array, and it may try to copy more data
+ * than is really available in <something>.
+ * Similarly,
+ *     umoven(tcp, addr, sizeof(sigset_t), &sigset)
+ * may be a bad idea: it'll try to read much more data than needed
+ * to fetch a sigset_t.
+ * Use (NSIG / 8) as a size instead.
+ */
+
 const char *
 signame(int sig)
 {
@@ -310,11 +310,21 @@ static const char *
 sprintsigmask(const char *str, sigset_t *mask, int rt)
 /* set might include realtime sigs */
 {
+       /* Was [8 * sizeof(sigset_t) * 8], but
+        * glibc sigset_t is huge (1024 bits = 128 *bytes*),
+        * and we were ending up with 8k (!) buffer here.
+        *
+        * No Unix system can have sig > 255
+        * (waitpid API won't be able to indicate death from one)
+        * and sig 0 doesn't exist either.
+        * Therefore max possible no of sigs is 255: 1..255
+        */
+       static char outstr[8 * 255];
+
        int i, nsigs;
        int maxsigs;
        const char *format;
        char *s;
-       static char outstr[8 * sizeof(sigset_t) * 8];
 
        strcpy(outstr, str);
        s = outstr + strlen(outstr);
@@ -1134,7 +1144,7 @@ sys_sigreturn(struct tcb *tcp)
                if (umove(tcp, usp+__SIGNAL_FRAMESIZE, &sc) < 0)
                        return 0;
                tcp->u_arg[0] = 1;
-               memcpy(&tcp->u_arg[1], &sc.oldmask[0], sizeof(sigset_t));
+               memcpy(&tcp->u_arg[1], &sc.oldmask[0], NSIG / 8);
        } else {
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
@@ -1177,14 +1187,15 @@ sys_sigreturn(struct tcb *tcp)
                if (umove(tcp, sp + 16 + SIGFRAME_SC_OFFSET, &sc) < 0)
                        return 0;
                tcp->u_arg[0] = 1;
-               memcpy(tcp->u_arg + 1, &sc.sc_mask, sizeof(sc.sc_mask));
+               memcpy(tcp->u_arg + 1, &sc.sc_mask, NSIG / 8);
        }
        else {
                sigset_t sigm;
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
-               memcpy(&sigm, tcp->u_arg + 1, sizeof(sigm));
+               sigemptyset(&sigm);
+               memcpy(&sigm, tcp->u_arg + 1, NSIG / 8);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }
@@ -1377,14 +1388,15 @@ sys_sigreturn(struct tcb *tcp)
                if (umove(tcp, sp + SIGFRAME_UC_OFFSET, &uc) < 0)
                        return 0;
                tcp->u_arg[0] = 1;
-               memcpy(tcp->u_arg + 1, &uc.uc_sigmask, sizeof(uc.uc_sigmask));
+               memcpy(tcp->u_arg + 1, &uc.uc_sigmask, NSIG / 8);
        }
        else {
                sigset_t sigm;
                tcp->u_rval = tcp->u_error = 0;
                if (tcp->u_arg[0] == 0)
                        return 0;
-               memcpy(&sigm, tcp->u_arg + 1, sizeof(sigm));
+               sigemptyset(&sigm);
+               memcpy(&sigm, tcp->u_arg + 1, NSIG / 8);
                tcp->auxstr = sprintsigmask("mask now ", &sigm, 0);
                return RVAL_NONE | RVAL_STR;
        }