add a bunch of util and clean up

4 files changed, 108 insertions, 72 deletions

diff --git a/snag/main.c b/snag/main.c
index eff1f2f..9804f99 100644
--- a/snag/main.c
+++ b/snag/main.c
@@ -1,16 +1,11 @@
 #include <stdio.h>
 
 #include "pkg_db.h"
-#include "util.h"
 
 void subcmd_install(char* pkgs[], size_t count);
 
 int main(int argc, char* argv[]) {
 
-    char buf[4096];
-    vstrcat(buf, "this ", "is", " a", " te", "st");
-    fprintf(stderr, "buf: %s\n", buf);
-
 	// run install subcommand with each argument as a package
 	subcmd_install(argv+1, argc-1);
 
@@ -28,7 +23,7 @@ void subcmd_install(char* pkgs[], size_t count) {
 		// load package description
 		package_info_t info;
 		if (load_package_info(&info, pkgid)) {
-			printf("Installing '%s'\n", info.attrs.id);
+			printf("Installing %s - %s\n", info.attrs.name, info.attrs.desc);
 		}
 	}
 }
diff --git a/snag/pkg_db.c b/snag/pkg_db.c
index ee11288..ad9eff3 100644
--- a/snag/pkg_db.c
+++ b/snag/pkg_db.c
@@ -1,9 +1,11 @@
 #include "pkg_db.h"
+#include "util.h"
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
 #include <sys/wait.h>
 
 #define PKG_DB "../packages"
@@ -11,86 +13,72 @@
 #define PKG_INFO_CMD "./get_pkg_attrs.sh"
 
 bool load_package_info(package_info_t* info, char* pkgid) {
+
     memset(info, 0, sizeof(*info));
+    size_t pkgid_len = strlen(pkgid);
 
 	// construct package description directory path and ensure it exists
-    size_t pkgid_len = strlen(pkgid);
-	size_t pkg_dir_len = PKG_DB_LEN + pkgid_len + 1;
-	char* pkg_dir = malloc(pkg_dir_len + 1);
-    if (!pkg_dir) {
-        fprintf(stderr, "Failed to alloc pkg_dir\n");
-        exit(1);
-    }
     // pkg_dir = "PKG_DB/pkgid"
-    memcpy(pkg_dir, PKG_DB, PKG_DB_LEN);
-    pkg_dir[PKG_DB_LEN] = '/';
-    memcpy(&pkg_dir[PKG_DB_LEN + 1], pkgid, pkgid_len + 1);
-
-	if (access(pkg_dir, F_OK) != 0) {
-        fprintf(stderr, "Package '%s' not found\n", pkgid);
-        free(pkg_dir);
-        return false;
-    }
+	size_t pkg_dir_len = PKG_DB_LEN + pkgid_len + 1;
+	char* pkg_dir = emalloc(pkg_dir_len + 1, "pkg_dir");
+	{
+		memcpy(pkg_dir, PKG_DB, PKG_DB_LEN);
+		pkg_dir[PKG_DB_LEN] = '/';
+		memcpy(pkg_dir + PKG_DB_LEN + 1, pkgid, pkgid_len);
+		pkg_dir[pkg_dir_len] = '\0';
+		if (access(pkg_dir, F_OK) != 0) {
+			eprintf("Package '%s' not found\n", pkgid);
+			free(pkg_dir);
+			return false;
+		}
+	}
 
 	// construct package description script path and ensure it exists
+	// script_path = "pkg_dir/pkgid.sh"
 	size_t script_path_len = pkg_dir_len + pkgid_len + 4;
-	info->script_path = malloc(script_path_len + 1);
-    if (!info->script_path) {
-        fprintf(stderr, "Failed to alloc info->script_path\n");
-        exit(1);
-    }
-
-    memcpy(info->script_path, pkg_dir, pkg_dir_len);
-    info->script_path[pkg_dir_len] = '/';
-    memcpy(&info->script_path[pkg_dir_len + 1], pkgid, pkgid_len);
-    memcpy(&info->script_path[script_path_len - 3], ".sh", 4);
-	free(pkg_dir);
-	if (access(info->script_path, F_OK) != 0) {
-        fprintf(stderr, "Package '%s' broken, doesn't have description script\n", pkgid);
-		free(info->script_path);
-		return false;
-    }
+	info->script_path = emalloc(script_path_len + 1, "info->script_path");
+	{
+		memcpy(info->script_path, pkg_dir, pkg_dir_len);
+		info->script_path[pkg_dir_len] = '/';
+		memcpy(&info->script_path[pkg_dir_len + 1], pkgid, pkgid_len);
+		memcpy(&info->script_path[script_path_len - 3], ".sh", 4);
+		free(pkg_dir);
+		if (access(info->script_path, F_OK) != 0) {
+			eprintf("Package '%s' broken, doesn't have description script\n", pkgid);
+			free(info->script_path);
+			return false;
+		}
+	}
 
+	// PIPE and FORK to run get pkg attrs script
     int pipefds[2] = {0};
-    if (pipe(pipefds) < 0) {
-        fprintf(stderr, "Failed to create pipe\n");
-        exit(1);
-    }
+    if (pipe(pipefds) < 0) error_out("failed to pipe: %s", strerror(errno));
     pid_t pid = fork();
-    if (pid < 0) {
-        fprintf(stderr, "Failed to create child process\n");
-        exit(1);
-    }
+    if (pid < 0) error_out("failed to fork: %s", strerror(errno));
 
+	// child proc
     if (pid == 0) {
+		// write my stdout the the pipe
         close(pipefds[0]);
         dup2(pipefds[1], STDOUT_FILENO);
         close(pipefds[1]);
-
+		// exec into get attr script
         char* argv[] = { PKG_INFO_CMD, info->script_path, NULL };
         char* envp[] = { NULL };
         execve(PKG_INFO_CMD, argv, envp);
-        fprintf(stderr, "execve failed\n");
-        exit(127);
+		error_out("execve failed");
     }
 
+	// wait for child to finish
     int wstatus;
-    if (waitpid(pid, &wstatus, 0) < 0) {
-        fprintf(stderr, "waitpid failed\n");
-        exit(1);
-    }
-    if (WEXITSTATUS(wstatus) == 127) {
-        exit(1);
-    }
+    if (waitpid(pid, &wstatus, 0) < 0) error_out("waitpid failed: %s", strerror(errno));
+	if (WEXITSTATUS(wstatus) != 0) error_out("failed to execute get pkg attr script");
 
+	// read all bytes from pipe
     ssize_t bytes_read = read(pipefds[0], info->package_attrs, sizeof(info->package_attrs));
-    if (bytes_read < 0) {
-        fprintf(stderr, "Failed to read from pipe\n");
-        exit(1);
-    }
-
-    free(info->script_path);
+    if (bytes_read < 0) error_out("Failed to read from pipe");
 
+	// read attributes from pipe data
     for (int i = 0; i < bytes_read;) {
         char atype = info->package_attrs[i];
         i++;
diff --git a/snag/util.c b/snag/util.c
index c4137f6..d8947a7 100644
--- a/snag/util.c
+++ b/snag/util.c
@@ -1,15 +1,58 @@
-#include <stdarg.h>
+#include <stdlib.h>
 #include <string.h>
+#include <stdio.h>
+
+#include "util.h"
+
+void eprintf(const char *format, ...) {
+	// send that shi to stderr
+    va_list args;
+    va_start(args, format);
+    vfprintf(stderr, format, args);
+    va_end(args);
+}
+
+void error_out(const char *format, ...) {
+    va_list args;
+    va_start(args, format);
+    vfprintf(stderr, format, args);
+    va_end(args);
+	fprintf(stderr, "\n");
+	exit(1);
+}
+
+void* emalloc(size_t size, char* alloc_reason) {
+	void* d = malloc(size);
+	if (d == NULL) error_out("Failed to allocate %s", alloc_reason);
+	return d;
+}
+
+char* vastrcat_(int dummy, ...) {
 
-void vstrcat_(char* dest, ...) {
     va_list args;
-    va_start(args, dest);
+    va_list args2;
+    va_start(args, dummy);
+	va_copy(args2, args);
+
+	// get len of output string
+	size_t len = 0;
     while (1) {
         char* arg = va_arg(args, char*);
         if (!arg) break;
-        memcpy(dest, arg, strlen(arg));
-        dest += strlen(arg);
+		len += strlen(arg);
     }
     va_end(args);
-    *dest = 0;
+
+	// allocate and build output
+	char* output = malloc(len + 1);
+	char* p = output;
+    while (1) {
+        char* arg = va_arg(args2, char*);
+        if (!arg) break;
+		memcpy(p, arg, strlen(arg));
+		p += strlen(arg);
+    }
+    va_end(args2);
+
+	return output;
 }
diff --git a/snag/util.h b/snag/util.h
index 88906cc..6f23607 100644
--- a/snag/util.h
+++ b/snag/util.h
@@ -1,6 +1,16 @@
 #ifndef UTIL_H
 #define UTIL_H
-#include <stdlib.h>
-#define vstrcat(dest, ...) vstrcat_(dest, __VA_ARGS__, NULL)
-void vstrcat_(char* dest, ...);
-#endif // UTIL_H
+
+#include <stdarg.h>
+#include <stddef.h>
+
+// utility for errors
+void eprintf(const char *format, ...) __attribute__((format(printf, 1, 2)));
+void error_out(const char *format, ...) __attribute__((format(printf, 1, 2))); // panic, as the kids say
+void* emalloc(size_t size, char* alloc_reason);
+
+// string functions
+char* vastrcat_(int dummy, ...);
+#define vastrcat(...) vastrcat_(0, __VA_ARGS__, NULL)
+
+#endif