C-based ftrace entry parser

src/ftracetool.c

@@ -17,6 +17,12 @@
 
 #define CLEANUP(f) __attribute__((cleanup(f)))
 
+enum Error_codes
+{
+    ER_COMMENT = 10000,
+    ER_PARSE_ERROR = 20000,
+};
+
 static const char gs_ftracetool_scm[] = {
 #include "ftracetool_scm.h"
 };
@@ -312,7 +318,8 @@ static int parse_ftrace_entry(const char *str,
                               char *pid_buf,
                               char *timestamp_buf,
                               char *probe_id_buf,
-                              char *args_buf)
+                              char **args,
+                              size_t *args_num)
 {
     // skip whitespaces
     while (isspace(*str))
@@ -321,7 +328,11 @@ static int parse_ftrace_entry(const char *str,
     }
     if (!*str)
     {
-        return -1;
+        return ER_PARSE_ERROR + 1;
+    }
+    if (*str == '#')
+    {
+        return ER_COMMENT;
     }
 
     char *out = comm_buf;
@@ -329,14 +340,14 @@ static int parse_ftrace_entry(const char *str,
     {
         if (!*str)
         {
-            return -2;
+            return ER_PARSE_ERROR + 2;
         }
         // TODO check out buf overflow
         *out++ = *str++;
     }
     if (!*str)
     {
-        return -3;
+        return ER_PARSE_ERROR + 3;
     }
     *out = 0;
     str++; // Skip '-
@@ -346,7 +357,7 @@ static int parse_ftrace_entry(const char *str,
     {
         if (!*str)
         {
-            return -4;
+            return ER_PARSE_ERROR + 4;
         }
 
         // TODO check out buf overflow
@@ -361,12 +372,12 @@ static int parse_ftrace_entry(const char *str,
     }
     if (!*str)
     {
-        return -5;
+        return ER_PARSE_ERROR + 5;
     }
     str++;
     if (!*str)
     {
-        return -6;
+        return ER_PARSE_ERROR + 6;
     }
 
     // skip whitespaces && flags
@@ -376,7 +387,7 @@ static int parse_ftrace_entry(const char *str,
     }
     if (!*str)
     {
-        return -7;
+        return ER_PARSE_ERROR + 7;
     }
 
     out = timestamp_buf;
@@ -384,7 +395,7 @@ static int parse_ftrace_entry(const char *str,
     {
         if (!*str)
         {
-            return -8;
+            return ER_PARSE_ERROR + 8;
         }
 
         // TODO check out buf overflow
@@ -394,7 +405,7 @@ static int parse_ftrace_entry(const char *str,
 
     if (*str != ':')
     {
-        return -9;
+        return ER_PARSE_ERROR + 9;
     }
     str++;
     // skip whitespaces
@@ -404,7 +415,7 @@ static int parse_ftrace_entry(const char *str,
     }
     if (!*str)
     {
-        return -10;
+        return ER_PARSE_ERROR + 10;
     }
 
     out = probe_id_buf;
@@ -412,7 +423,7 @@ static int parse_ftrace_entry(const char *str,
     {
         if (!*str)
         {
-            return -11;
+            return ER_PARSE_ERROR + 11;
         }
         // TODO check out buf overflow
         *out++ = *str++;
@@ -426,25 +437,44 @@ static int parse_ftrace_entry(const char *str,
     }
     if (!*str)
     {
-        return -12;
+        return ER_PARSE_ERROR + 12;
     }
     str++;
     if (!*str)
     {
-        return -13;
+        return ER_PARSE_ERROR + 13;
     }
 
-    out = args_buf;
+    size_t arg_num = 0;
     while (*str)
     {
+        const char *start = NULL;
+        while (*str && *str != '=')
+        {
+            str++;
+        }
         if (!*str)
         {
-            return -14;
+            break;
         }
-        // TODO check out buf overflow
-        *out++ = *str++;
+        start = str + 1;
+        while (*str && *str != ' ')
+        {
+            str++;
         }
-    *out = 0;
+        const char *end = str;
+
+        const size_t string_length = end - start + 2;
+        args[arg_num] = calloc(1, string_length);
+        if (!args[arg_num])
+        {
+            return ER_PARSE_ERROR + 15;
+        }
+        memcpy(args[arg_num], start, string_length - 1);
+        arg_num++;
+    }
+
+    *args_num = arg_num;
 
     return 0;
 }
@@ -452,7 +482,6 @@ static int parse_ftrace_entry(const char *str,
 static sexp
 sexp_parse_ftrace_entry_stub(sexp ctx, sexp self, sexp_sint_t n, sexp arg0)
 {
-    sexp res;
     int ret = 0;
     if (!sexp_stringp(arg0))
     {
@@ -462,15 +491,23 @@ sexp_parse_ftrace_entry_stub(sexp ctx, sexp self, sexp_sint_t n, sexp arg0)
     char pid_buf[32];
     char timestamp_buf[64];
     char probe_id_buf[64];
-    char args[128];
+    char *args[128];
+    size_t args_num = 0;
     ret = parse_ftrace_entry(sexp_string_data(arg0),
                              comm_buf,
                              pid_buf,
                              timestamp_buf,
                              probe_id_buf,
-                             args);
+                             args,
+                             &args_num);
+    if (ret == ER_COMMENT)
+    {
+        return SEXP_FALSE;
+    }
     if (ret)
     {
+        fprintf(stderr, "parse_ftrace_entry failed with %d\n", ret);
+        fprintf(stderr, "%s\n", sexp_string_data(arg0));
         return SEXP_FALSE;
     }
     unsigned long pid = atoi(pid_buf);
@@ -479,6 +516,14 @@ sexp_parse_ftrace_entry_stub(sexp ctx, sexp self, sexp_sint_t n, sexp arg0)
     char *frac = dot + 1;
     double timestamp = atol(timestamp_buf) + atol(frac) / 1000000.;
 
+    sexp prev = SEXP_NULL;
+    sexp head = SEXP_NULL;
+    for (ssize_t arg_num = args_num - 1; arg_num >= 0; arg_num--)
+    {
+        head = sexp_cons(ctx, sexp_c_string(ctx, args[arg_num], -1), prev);
+        prev = head;
+    }
+
     return sexp_cons(
         ctx,
         sexp_c_string(ctx, comm_buf, -1),
@@ -488,9 +533,7 @@ sexp_parse_ftrace_entry_stub(sexp ctx, sexp self, sexp_sint_t n, sexp arg0)
                             sexp_make_flonum(ctx, timestamp),
                             sexp_cons(ctx,
                                       sexp_c_string(ctx, probe_id_buf, -1),
-                                      sexp_cons(ctx,
-                                                sexp_c_string(ctx, args, -1),
-                                                SEXP_NULL)))));
+                                      sexp_cons(ctx, head, SEXP_NULL)))));
 }
 
 static int register_lookup_symbol_in_file(sexp ctx)

src/ftracetool.scm

@@ -243,8 +243,7 @@
                            (timestamp (list-ref match 2))
                            (probe-name (list-ref match 3))
                            (args (list-ref match 4))
-                           (parsed-args (parse-arguments args))
-                           (trace-event (make-trace-event timestamp probe-name pid (parse-arguments args))))
+                           (trace-event (make-trace-event timestamp probe-name pid args)))
                       (loop (read-line p) (cons trace-event events) (+ 1 n)))
                     (loop (read-line p) events n)))))))))))