Make svg-flatten auto-search for cargo dependencies in all call sites

svg-flatten/src/util.cpp

@@ -0,0 +1,84 @@
+
+#include <pwd.h>
+#include <sys/types.h>
+#include <string>
+#include <iostream>
+
+#include <subprocess.h>
+#include <filesystem>
+
+#include "util.h"
+
+using namespace std;
+
+int gerbolyze::run_cargo_command(const char *cmd_name, const char *cmdline[], const char *envvar) {
+    const char *homedir;
+    if ((homedir = getenv("HOME")) == NULL) {
+        homedir = getpwuid(getuid())->pw_dir;
+    }
+    string homedir_s(homedir);
+    string cargo_bin_dir = homedir_s + "/.cargo/bin/" + cmd_name;
+
+    bool found = false;
+    int proc_rc = -1;
+    for (int i=0; i<3; i++) {
+        const char *envvar_val;
+        switch (i) {
+        case 0:
+            if ((envvar_val = getenv(envvar)) == NULL) {
+                continue;
+            } else {
+                cmdline[0] = envvar_val;
+            }
+            break;
+
+        case 1:
+            cmdline[0] = cmd_name;
+            break;
+
+        case 2:
+            cmdline[0] = cargo_bin_dir.c_str();
+            break;
+        }
+
+        struct subprocess_s subprocess;
+        int rc = subprocess_create(cmdline, subprocess_option_inherit_environment, &subprocess);
+        if (rc) {
+            cerr << "Error calling " << cmd_name << endl;
+            return EXIT_FAILURE;
+        }
+
+        proc_rc = -1;
+        rc = subprocess_join(&subprocess, &proc_rc);
+        if (rc) {
+            cerr << "Error calling " << cmd_name << endl;
+            return EXIT_FAILURE;
+        }
+
+        rc = subprocess_destroy(&subprocess);
+        if (rc) {
+            cerr << "Error calling " << cmd_name << endl;
+            return EXIT_FAILURE;
+        }
+
+        /* Fail if the command given in the environment variable could not be found. */
+        if (i > 0 && proc_rc == 255) {
+            continue;
+        }
+        found = true;
+        break;
+    }
+
+    if (!found) {
+        cerr << "Error: Cannot find " << cmd_name << ". Is it installed and in $PATH?" << endl;
+        return EXIT_FAILURE;
+    }
+
+    if (proc_rc) {
+        cerr << cmd_name << " returned an error code: " << proc_rc << endl;
+        return EXIT_FAILURE;
+    }
+
+    return 0;
+}
+