process: fix duplicate output, bug fixes

* flush all streams before `fork()` to ensure pending output does
  not get duplicated.  Redirecting compiler or tester output to a
  file or a pipe produced extra output.
* test and report `fork()` failures
* pass `nil` instead of `0` as last argument to `execl` to ensure
  a pointer is passed instead of an `int` that has a different size
  on 64-bit targets.

Author: chqrlie

common/process_utils.c2

@@ -50,6 +50,12 @@ fn void child_error(i32 fd, const char* msg) {
 }
 
 public fn i32 run(const char* path, const char* cmd, const char* logfile) {
+    // run a command in a child process
+    // - stdout and stderr are redirected together to a logfile
+
+    // flush all streams before forking to avoid duplicate output
+    fflush(nil);
+
     i32[2] error_pipe;
     if (pipe(error_pipe)) {
         fprintf(stderr, "pipe() failed: %s\n", strerror(*errno2()));
@@ -66,6 +72,10 @@ public fn i32 run(const char* path, const char* cmd, const char* logfile) {
     }
 
     Pid child_pid = fork();
+    if (child_pid == -1) {
+        fprintf(stderr, "fork() failed: %s\n", strerror(*errno2()));
+        return -1;
+    }
     if (child_pid == 0) {   // child
         char[256] errmsg;
 
@@ -196,6 +206,12 @@ fn const char* find_bin(char *dest, usize size, const char* name) {
 
 public fn i32 run_args(const char* path, const char* cmd, const char* logfile, const char* args)
 {
+    // run a command in a child process
+    // - stdout and stderr are redirected together to a logfile
+
+    // flush all streams before forking to avoid duplicate output
+    fflush(nil);
+
     i32[2] error_pipe;
     if (pipe(error_pipe)) {
         fprintf(stderr, "pipe() failed: %s\n", strerror(*errno2()));
@@ -212,6 +228,10 @@ public fn i32 run_args(const char* path, const char* cmd, const char* logfile, c
     }
 
     Pid child_pid = fork();
+    if (child_pid == -1) {
+        fprintf(stderr, "fork() failed: %s\n", strerror(*errno2()));
+        return -1;
+    }
     if (child_pid == 0) {   // child
         char[256] errmsg;
 

common/process_utils2.c2

@@ -27,6 +27,13 @@ import string_utils;
 
 public fn i32 run2(const char* path, const char* cmd, const char* args, char* output)
 {
+    // run a command in a child process
+    // - stdout and stderr are redirected together and captured into the `output` buffer
+    // TODO merge with run_args.
+
+    // flush all streams before forking to avoid duplicate output
+    fflush(nil);
+
     i32[2] error_pipe;
     if (pipe(error_pipe)) {
         fprintf(stderr, "pipe() failed: %s\n", strerror(*errno2()));
@@ -70,7 +77,6 @@ public fn i32 run2(const char* path, const char* cmd, const char* args, char* ou
         }
 
         // redirect output
-        fflush(stdout);
         close(STDOUT_FILENO);
         if (dup(output_pipe[1]) == -1) {
             sprintf(errmsg, "dup(): %s", strerror(*errno2()));

generator/qbe_generator.c2

@@ -596,11 +596,19 @@ public fn void generate(const char* target,
 
 public fn void build(const char* output_dir)
 {
+    const char* make = "make";
+#if SYSTEM_FREEBSD
+    make = "gmake";
+#endif
+#if SYSTEM_OPENBSD
+    make = "gmake";
+#endif
+
     // TODO put in aux-pool? (lowers stack-size)
     char[constants.Max_path] dir;
     stdio.sprintf(dir, "%s/%s/", output_dir, QBE_Dir);
 
-    i32 retval = process_utils.run(dir, "/usr/bin/make", LogFile);
+    i32 retval = process_utils.run_args(dir, make, LogFile, "");
     if (retval != 0) {
         console.error("error during external QBE compilation");
         console.log("see %s%s for details", dir, LogFile);

tools/tester/test_db.c2

@@ -751,6 +751,9 @@ public fn bool Db.parse(Db* db) {
 }
 
 public fn void Db.testFile(Db* db) {
+    // flush all streams before forking to avoid duplicate output
+    fflush(nil);
+
     i32[2] pipe_stdout;
     if (pipe(pipe_stdout) == -1) {
         fprintf(stderr, "pipe() failed: %s\n", strerror(*errno2()));
@@ -775,7 +778,7 @@ public fn void Db.testFile(Db* db) {
         while ((dup2(pipe_stderr[1], STDERR_FILENO) == -1) && (*errno2() == EINTR)) {}
         close(pipe_stderr[1]);
         close(pipe_stderr[0]);
-        execl(db.c2c_cmd, "c2c", "-d", db.tmp_dir, "--test", 0);
+        execl(db.c2c_cmd, "c2c", "-d", db.tmp_dir, "--test", nil);
         fprintf(stderr, "execl() failed: %s\n", strerror(*errno2()));
         exit(127); /* only if execv fails */
     } else { // parent