linux-user: factor out reading of /proc/self/maps

Unfortunately reading /proc/self/maps is still considered the gold
standard for a process finding out about it's own memory layout. As we
will want this data in other contexts soon factor out the code to read
and parse the data. Rather than just blindly copying the existing
sscanf based code we use a more modern glib version of the parsing
code to make a more general purpose map structure.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200403191150.863-9-alex.bennee@linaro.org>

1 files changed, 28 insertions, 30 deletions

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index b679bc6b13..5f11787294 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -117,6 +117,7 @@
 
 #include "qemu.h"
 #include "qemu/guest-random.h"
+#include "qemu/selfmap.h"
 #include "user/syscall-trace.h"
 #include "qapi/error.h"
 #include "fd-trans.h"
@@ -7232,45 +7233,45 @@ static int open_self_maps(void *cpu_env, int fd)
 {
     CPUState *cpu = env_cpu((CPUArchState *)cpu_env);
     TaskState *ts = cpu->opaque;
-    FILE *fp;
-    char *line = NULL;
-    size_t len = 0;
-    ssize_t read;
+    GSList *map_info = read_self_maps();
+    GSList *s;
 
-    fp = fopen("/proc/self/maps", "r");
-    if (fp == NULL) {
-        return -1;
-    }
+    for (s = map_info; s; s = g_slist_next(s)) {
+        MapInfo *e = (MapInfo *) s->data;
 
-    while ((read = getline(&line, &len, fp)) != -1) {
-        int fields, dev_maj, dev_min, inode;
-        uint64_t min, max, offset;
-        char flag_r, flag_w, flag_x, flag_p;
-        char path[512] = "";
-        fields = sscanf(line, "%"PRIx64"-%"PRIx64" %c%c%c%c %"PRIx64" %x:%x %d"
-                        " %512s", &min, &max, &flag_r, &flag_w, &flag_x,
-                        &flag_p, &offset, &dev_maj, &dev_min, &inode, path);
-
-        if ((fields < 10) || (fields > 11)) {
-            continue;
-        }
-        if (h2g_valid(min)) {
+        if (h2g_valid(e->start)) {
+            unsigned long min = e->start;
+            unsigned long max = e->end;
             int flags = page_get_flags(h2g(min));
-            max = h2g_valid(max - 1) ? max : (uintptr_t)g2h(GUEST_ADDR_MAX) + 1;
+            const char *path;
+
+            max = h2g_valid(max - 1) ?
+                max : (uintptr_t) g2h(GUEST_ADDR_MAX) + 1;
+
             if (page_check_range(h2g(min), max - min, flags) == -1) {
                 continue;
             }
+
             if (h2g(min) == ts->info->stack_limit) {
-                pstrcpy(path, sizeof(path), "      [stack]");
+                path = "      [stack]";
+            } else {
+                path = e->path;
             }
+
             dprintf(fd, TARGET_ABI_FMT_ptr "-" TARGET_ABI_FMT_ptr
-                    " %c%c%c%c %08" PRIx64 " %02x:%02x %d %s%s\n",
-                    h2g(min), h2g(max - 1) + 1, flag_r, flag_w,
-                    flag_x, flag_p, offset, dev_maj, dev_min, inode,
-                    path[0] ? "         " : "", path);
+                    " %c%c%c%c %08" PRIx64 " %s %"PRId64" %s%s\n",
+                    h2g(min), h2g(max - 1) + 1,
+                    e->is_read ? 'r' : '-',
+                    e->is_write ? 'w' : '-',
+                    e->is_exec ? 'x' : '-',
+                    e->is_priv ? 'p' : '-',
+                    (uint64_t) e->offset, e->dev, e->inode,
+                    path ? "         " : "", path ? path : "");
         }
     }
 
+    free_self_maps(map_info);
+
 #ifdef TARGET_VSYSCALL_PAGE
     /*
      * We only support execution from the vsyscall page.
@@ -7281,9 +7282,6 @@ static int open_self_maps(void *cpu_env, int fd)
             TARGET_VSYSCALL_PAGE, TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE);
 #endif
 
-    free(line);
-    fclose(fp);
-
     return 0;
 }