[PATCH 2/2] linux user: refactored is proc functions for syscalls

[Andrew Aladjev <aladjev.andrew@gmail.com>]

Signed-off-by: Andrew Aladjev <aladjev.andrew@gmail.com>
---
 linux-user/syscall.c | 81 ++++++++++++++++++++++++++++++--------------
 1 file changed, 56 insertions(+), 25 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 3d8c57522d..7b4d7cc197 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7482,38 +7482,69 @@ static int open_self_auxv(void *cpu_env, int fd)
     return 0;
 }
 
-static int is_proc_myself(const char *filename, const char *entry)
-{
-    if (!strncmp(filename, "/proc/", strlen("/proc/"))) {
-        filename += strlen("/proc/");
-        if (!strncmp(filename, "self/", strlen("self/"))) {
-            filename += strlen("self/");
-        } else if (*filename >= '1' && *filename <= '9') {
-            char myself[80];
-            snprintf(myself, sizeof(myself), "%d/", getpid());
-            if (!strncmp(filename, myself, strlen(myself))) {
-                filename += strlen(myself);
-            } else {
-                return 0;
-            }
-        } else {
-            return 0;
-        }
-        if (!strcmp(filename, entry)) {
-            return 1;
+#define PROC "/proc/"
+#define SELF "self/"
+
+#define STARTS_WITH(path, CONSTANT) (              \
+    strlen(path) >= strlen(CONSTANT) &&            \
+    strncmp(path, CONSTANT, strlen(CONSTANT)) == 0 \
+)
+
+static inline char *scope_to_proc(const char *path)
+{
+    if (STARTS_WITH(path, PROC)) {
+        return (char *)path + strlen(PROC);
+    }
+
+    return NULL;
+}
+
+static inline char *scope_to_proc_myself(const char *path)
+{
+    char *scope_path = scope_to_proc(path);
+    if (scope_path == NULL) {
+        return NULL;
+    }
+
+    if (STARTS_WITH(scope_path, SELF)) {
+        return scope_path + strlen(SELF);
+    }
+
+    if (strlen(scope_path) >= 1 &&
+        *scope_path >= '1' && *scope_path <= '9') {
+        char pid_path[80];
+        snprintf(pid_path, sizeof(pid_path), "%d/", getpid());
+        if (STARTS_WITH(scope_path, pid_path)) {
+            return scope_path + strlen(pid_path);
         }
     }
-    return 0;
+
+    return NULL;
 }
 
 #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN) || \
     defined(TARGET_SPARC) || defined(TARGET_M68K) || defined(TARGET_HPPA)
-static int is_proc(const char *filename, const char *entry)
+static int is_proc(const char *path, const char *entry)
 {
-    return strcmp(filename, entry) == 0;
+    char *scope_path = scope_to_proc(path);
+    if (scope_path == NULL) {
+        return 0;
+    }
+
+    return strcmp(scope_path, entry) == 0;
 }
 #endif
 
+static int is_proc_myself(const char *path, const char *entry)
+{
+    char *scope_path = scope_to_proc_myself(path);
+    if (scope_path == NULL) {
+        return 0;
+    }
+
+    return strcmp(scope_path, entry) == 0;
+}
+
 #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
 static int open_net_route(void *cpu_env, int fd)
 {
@@ -7601,13 +7632,13 @@ static int do_openat(void *cpu_env, int dirfd, const char *pathname, int flags,
         { "auxv", open_self_auxv, is_proc_myself },
         { "cmdline", open_self_cmdline, is_proc_myself },
 #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
-        { "/proc/net/route", open_net_route, is_proc },
+        { "net/route", open_net_route, is_proc },
 #endif
 #if defined(TARGET_SPARC) || defined(TARGET_HPPA)
-        { "/proc/cpuinfo", open_cpuinfo, is_proc },
+        { "cpuinfo", open_cpuinfo, is_proc },
 #endif
 #if defined(TARGET_M68K)
-        { "/proc/hardware", open_hardware, is_proc },
+        { "hardware", open_hardware, is_proc },
 #endif
         { NULL, NULL, NULL }
     };
-- 
2.26.2