nlattr: add UID/GID netlink attribute decoders

[strace] / ucopy.c

diff --git a/ucopy.c b/ucopy.c
index b2d5d8110077ceb9e16873d4bf70ee07778da205..dafc1e4ed524061ddac568c6caa884e375bce3c5 100644 (file)
--- a/ucopy.c
+++ b/ucopy.c
@@ -6,7 +6,7 @@
  * Copyright (c) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
  *                     Linux for s390 port by D.J. Barrow
  *                    <barrow_dj@mail.yahoo.com,djbarrow@de.ibm.com>
- * Copyright (c) 1999-2017 The strace developers.
+ * Copyright (c) 1999-2018 The strace developers.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -106,44 +106,18 @@ static int
 umoven_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
                void *laddr)
 {
-       unsigned int n, m, nread;
-       union {
-               long val;
-               char x[sizeof(long)];
-       } u;
-
-       nread = 0;
-       if (addr & (sizeof(long) - 1)) {
-               /* addr not a multiple of sizeof(long) */
-               n = addr & (sizeof(long) - 1);  /* residue */
-               addr &= -sizeof(long);          /* aligned address */
-               errno = 0;
-               u.val = ptrace(PTRACE_PEEKDATA, pid, addr, 0);
-               switch (errno) {
-                       case 0:
-                               break;
-                       case ESRCH: case EINVAL:
-                               /* these could be seen if the process is gone */
-                               return -1;
-                       case EFAULT: case EIO: case EPERM:
-                               /* address space is inaccessible */
-                               return -1;
-                       default:
-                               /* all the rest is strange and should be reported */
-                               perror_msg("umoven: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
-                                           pid, addr);
-                               return -1;
-               }
-               m = MIN(sizeof(long) - n, len);
-               memcpy(laddr, &u.x[n], m);
-               addr += sizeof(long);
-               laddr += m;
-               nread += m;
-               len -= m;
-       }
+       unsigned int nread = 0;
+       unsigned int residue = addr & (sizeof(long) - 1);
+
        while (len) {
+               addr &= -sizeof(long);          /* aligned address */
+
                errno = 0;
-               u.val = ptrace(PTRACE_PEEKDATA, pid, addr, 0);
+               union {
+                       long val;
+                       char x[sizeof(long)];
+               } u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };
+
                switch (errno) {
                        case 0:
                                break;
@@ -163,8 +137,10 @@ umoven_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
                                            pid, addr);
                                return -1;
                }
-               m = MIN(sizeof(long), len);
-               memcpy(laddr, u.x, m);
+
+               unsigned int m = MIN(sizeof(long) - residue, len);
+               memcpy(laddr, &u.x[residue], m);
+               residue = 0;
                addr += sizeof(long);
                laddr += m;
                nread += m;
@@ -225,51 +201,19 @@ static int
 umovestr_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
                  void *laddr)
 {
-       const unsigned long x01010101 = (unsigned long) 0x0101010101010101ULL;
-       const unsigned long x80808080 = (unsigned long) 0x8080808080808080ULL;
-
-       unsigned int n, m, nread;
-       union {
-               unsigned long val;
-               char x[sizeof(long)];
-       } u;
-
-       nread = 0;
-       if (addr & (sizeof(long) - 1)) {
-               /* addr not a multiple of sizeof(long) */
-               n = addr & (sizeof(long) - 1);  /* residue */
-               addr &= -sizeof(long);          /* aligned address */
-               errno = 0;
-               u.val = ptrace(PTRACE_PEEKDATA, pid, addr, 0);
-               switch (errno) {
-                       case 0:
-                               break;
-                       case ESRCH: case EINVAL:
-                               /* these could be seen if the process is gone */
-                               return -1;
-                       case EFAULT: case EIO: case EPERM:
-                               /* address space is inaccessible */
-                               return -1;
-                       default:
-                               /* all the rest is strange and should be reported */
-                               perror_msg("umovestr: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
-                                           pid, addr);
-                               return -1;
-               }
-               m = MIN(sizeof(long) - n, len);
-               memcpy(laddr, &u.x[n], m);
-               while (n & (sizeof(long) - 1))
-                       if (u.x[n++] == '\0')
-                               return 1;
-               addr += sizeof(long);
-               laddr += m;
-               nread += m;
-               len -= m;
-       }
+       unsigned int nread = 0;
+       unsigned int residue = addr & (sizeof(long) - 1);
+       void *const orig_addr = laddr;
 
        while (len) {
+               addr &= -sizeof(long);          /* aligned address */
+
                errno = 0;
-               u.val = ptrace(PTRACE_PEEKDATA, pid, addr, 0);
+               union {
+                       unsigned long val;
+                       char x[sizeof(long)];
+               } u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };
+
                switch (errno) {
                        case 0:
                                break;
@@ -289,11 +233,13 @@ umovestr_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
                                           pid, addr);
                                return -1;
                }
-               m = MIN(sizeof(long), len);
-               memcpy(laddr, u.x, m);
-               /* "If a NUL char exists in this word" */
-               if ((u.val - x01010101) & ~u.val & x80808080)
-                       return 1;
+
+               unsigned int m = MIN(sizeof(long) - residue, len);
+               memcpy(laddr, &u.x[residue], m);
+               while (residue < sizeof(long))
+                       if (u.x[residue++] == '\0')
+                               return (laddr - orig_addr) + residue;
+               residue = 0;
                addr += sizeof(long);
                laddr += m;
                nread += m;
@@ -307,8 +253,7 @@ umovestr_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
  * Like `umove' but make the additional effort of looking
  * for a terminating zero byte.
  *
- * Returns < 0 on error, > 0 if NUL was seen,
- * (TODO if useful: return count of bytes including NUL),
+ * Returns < 0 on error, strlen + 1  if NUL was seen,
  * else 0 if len bytes were read but no NUL byte seen.
  *
  * Note: there is no guarantee we won't overwrite some bytes
@@ -344,8 +289,10 @@ umovestr(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
 
                int r = vm_read_mem(pid, laddr, addr, chunk_len);
                if (r > 0) {
-                       if (memchr(laddr, '\0', r))
-                               return 1;
+                       char *nul_addr = memchr(laddr, '\0', r);
+
+                       if (nul_addr)
+                               return (nul_addr - laddr) + 1;
                        addr += r;
                        laddr += r;
                        nread += r;
@@ -359,7 +306,7 @@ umovestr(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
                                if (!nread)
                                        return umovestr_peekdata(pid, addr,
                                                                 len, laddr);
-                               /* fall through */
+                               ATTRIBUTE_FALLTHROUGH;
                        case EFAULT: case EIO:
                                /* address space is inaccessible */
                                if (nread)