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>

2 files changed, 79 insertions, 0 deletions

diff --git a/util/Makefile.objs b/util/Makefile.objs
index 6718a38b61..fe339c2636 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -63,3 +63,4 @@ util-obj-y += guest-random.o
 util-obj-$(CONFIG_GIO) += dbus.o
 dbus.o-cflags = $(GIO_CFLAGS)
 dbus.o-libs = $(GIO_LIBS)
+util-obj-$(CONFIG_USER_ONLY) += selfmap.o
diff --git a/util/selfmap.c b/util/selfmap.c
new file mode 100644
index 0000000000..2ec99dfdda
--- /dev/null
+++ b/util/selfmap.c
@@ -0,0 +1,78 @@
+/*
+ * Utility function to get QEMU's own process map
+ *
+ * Copyright (c) 2020 Linaro Ltd
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "qemu/selfmap.h"
+
+GSList *read_self_maps(void)
+{
+    gchar *maps;
+    GSList *map_info = NULL;
+
+    if (g_file_get_contents("/proc/self/maps", &maps, NULL, NULL)) {
+        gchar **lines = g_strsplit(maps, "\n", 0);
+        int i, entries = g_strv_length(lines);
+
+        for (i = 0; i < entries; i++) {
+            gchar **fields = g_strsplit(lines[i], " ", 6);
+            if (g_strv_length(fields) > 4) {
+                MapInfo *e = g_new0(MapInfo, 1);
+                int errors;
+                const char *end;
+
+                errors  = qemu_strtoul(fields[0], &end, 16, &e->start);
+                errors += qemu_strtoul(end + 1, NULL, 16, &e->end);
+
+                e->is_read  = fields[1][0] == 'r';
+                e->is_write = fields[1][1] == 'w';
+                e->is_exec  = fields[1][2] == 'x';
+                e->is_priv  = fields[1][3] == 'p';
+
+                errors += qemu_strtoul(fields[2], NULL, 16, &e->offset);
+                e->dev = g_strdup(fields[3]);
+                errors += qemu_strtou64(fields[4], NULL, 10, &e->inode);
+
+                /*
+                 * The last field may have leading spaces which we
+                 * need to strip.
+                 */
+                if (g_strv_length(fields) == 6) {
+                    e->path = g_strdup(g_strchug(fields[5]));
+                }
+                map_info = g_slist_prepend(map_info, e);
+            }
+
+            g_strfreev(fields);
+        }
+        g_strfreev(lines);
+        g_free(maps);
+    }
+
+    /* ensure the map data is in the same order we collected it */
+    return g_slist_reverse(map_info);
+}
+
+/**
+ * free_self_maps:
+ * @info: a GSlist
+ *
+ * Free a list of MapInfo structures.
+ */
+static void free_info(gpointer data)
+{
+    MapInfo *e = (MapInfo *) data;
+    g_free(e->dev);
+    g_free(e->path);
+    g_free(e);
+}
+
+void free_self_maps(GSList *info)
+{
+    g_slist_free_full(info, &free_info);
+}