memory analyzer: fail when gdb cannot be started

When gdb wasn't available, the forked child would not terminate and the
parent would wait forever.

Also make the unit tests less fragile by not relying on a particular
directory that they are being run from. Test files had to be loaded from
a specific location; instead, place them in the source code and generate
temporary files at runtime.

Author: tautschnig

src/memory-analyzer/gdb_api.cpp

@@ -132,13 +132,13 @@ void gdb_apit::create_gdb_process()
 
     // Only reachable, if execvp failed
     int errno_value = errno;
-    dprintf(pipe_output[1], "errno in child: %s\n", strerror(errno_value));
+    dprintf(pipe_output[1], "Starting gdb failed: %s\n", strerror(errno_value));
+    dprintf(pipe_output[1], "(gdb) \n");
+    throw gdb_interaction_exceptiont("could not run gdb");
   }
   else
   {
     // parent process
-    gdb_state = gdb_statet::CREATED;
-
     close(pipe_input[0]);
     close(pipe_output[1]);
 
@@ -149,6 +149,11 @@ void gdb_apit::create_gdb_process()
     command_stream = fdopen(pipe_input[1], "w");
 
     std::string line = read_most_recent_line();
+    if(has_prefix(line, "Starting gdb failed:"))
+      throw gdb_interaction_exceptiont(line);
+
+    gdb_state = gdb_statet::CREATED;
+
     CHECK_RETURN(
       has_prefix(line, R"(~"done)") ||
       has_prefix(line, R"(~"Reading)"));

unit/memory-analyzer/gdb_api.cpp

@@ -18,13 +18,61 @@ Author: Malte Mues <[email protected]>
 #include <iostream>
 
 #include <memory-analyzer/gdb_api.cpp>
+
 #include <util/run.h>
+#include <util/tempfile.h>
 
-void compile_test_file()
+struct compile_test_filet
 {
-  REQUIRE(
-    run("gcc", {"gcc", "-g", "-o", "test", "memory-analyzer/test.c"}) == 0);
-}
+  compile_test_filet() : compiled("test", "")
+  {
+    temporary_filet tmp("test", ".c");
+    std::ofstream of(tmp().c_str());
+    REQUIRE(of.is_open());
+
+    of << "int x;\n"
+          "float y;\n"
+          "char z;\n"
+          "\n"
+          "char *s = \"abc\";\n"
+          "int *p;\n"
+          "void *vp;\n"
+          "int *np = 0;\n"
+          "void *vp_string;\n"
+          "\n"
+          "void checkpoint()\n"
+          "{\n"
+          "}\n"
+          "void checkpoint2()\n"
+          "{\n"
+          "}\n"
+          "\n"
+          "void func()\n"
+          "{\n"
+          "  checkpoint2();\n"
+          "}\n"
+          "\n"
+          "int main()\n"
+          "{\n"
+          "  x = 8;\n"
+          "  y = 2.5;\n"
+          "  z = 'c';\n"
+          "\n"
+          "  p = &x;\n"
+          "  vp = (void *)&x;\n"
+          "  vp_string = s;\n"
+          "\n"
+          "  checkpoint();\n"
+          "\n"
+          "  return 0;\n"
+          "}\n";
+    of.close();
+
+    REQUIRE(run("gcc", {"gcc", "-g", "-o", compiled(), tmp()}) == 0);
+  }
+
+  temporary_filet compiled;
+};
 
 void check_for_gdb()
 {
@@ -46,10 +94,10 @@ class gdb_api_testt : public gdb_apit
 void gdb_api_internals_test()
 {
   check_for_gdb();
-  compile_test_file();
+  compile_test_filet test_file;
 
   std::vector<std::string> args;
-  args.push_back("test");
+  args.push_back(test_file.compiled());
 
   SECTION("parse gdb output record")
   {
@@ -67,9 +115,34 @@ void gdb_api_internals_test()
 
   SECTION("read a line from an input stream")
   {
+    temporary_filet tmp("input", ".txt");
+    std::ofstream of(tmp().c_str());
+    REQUIRE(of.is_open());
+
+    of << "abc\n"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+          "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
+          "xyz";
+    of.close();
+
     gdb_api_testt gdb_api(args);
 
-    FILE *f = fopen("memory-analyzer/input.txt", "r");
+    FILE *f = fopen(tmp().c_str(), "r");
     gdb_api.response_stream = f;
 
     std::string line = gdb_api.read_next_line();
@@ -102,10 +175,10 @@ TEST_CASE("gdb api internals test", "[core][memory-analyzer]")
 TEST_CASE("gdb api test", "[core][memory-analyzer]")
 {
   check_for_gdb();
-  compile_test_file();
+  compile_test_filet test_file;
 
   std::vector<std::string> args;
-  args.push_back("test");
+  args.push_back(test_file.compiled());
 
   {
     gdb_apit gdb_api(args, true);