portable server with embedded for musl has different feature

packaging/musl/postgresql-launcher.c

@@ -0,0 +1,92 @@
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static void fail(const char *message)
+{
+    fprintf(stderr, "embedded PostgreSQL launcher: %s\n", message);
+    exit(127);
+}
+
+static void join_path(char *destination, size_t capacity, const char *left, const char *right)
+{
+    int length = snprintf(destination, capacity, "%s/%s", left, right);
+    if (length < 0 || (size_t) length >= capacity)
+        fail("installation path is too long");
+}
+
+int main(int argc, char **argv)
+{
+    char executable[PATH_MAX];
+    ssize_t executable_length = readlink("/proc/self/exe", executable, sizeof(executable) - 1);
+    if (executable_length < 0) {
+        perror("embedded PostgreSQL launcher: /proc/self/exe");
+        return 127;
+    }
+    executable[executable_length] = '\0';
+
+    char *tool = strrchr(executable, '/');
+    if (tool == NULL || tool[1] == '\0')
+        fail("cannot determine the requested PostgreSQL tool");
+    tool++;
+
+    char root[PATH_MAX];
+    if ((size_t) executable_length >= sizeof(root))
+        fail("installation path is too long");
+    memcpy(root, executable, (size_t) executable_length + 1);
+
+    char *bin_separator = strrchr(root, '/');
+    if (bin_separator == NULL)
+        fail("cannot determine the PostgreSQL installation directory");
+    *bin_separator = '\0';
+    char *root_separator = strrchr(root, '/');
+    if (root_separator == NULL)
+        fail("cannot determine the PostgreSQL installation directory");
+    *root_separator = '\0';
+
+    char loader[PATH_MAX];
+    char library_path[PATH_MAX];
+    char real_tool[PATH_MAX];
+    join_path(loader, sizeof(loader), root, "lib/ld-musl-x86_64.so.1");
+    join_path(library_path, sizeof(library_path), root, "lib");
+
+    char real_tool_relative[PATH_MAX];
+    int relative_length = snprintf(
+        real_tool_relative,
+        sizeof(real_tool_relative),
+        "libexec/%s",
+        tool
+    );
+    if (relative_length < 0 || (size_t) relative_length >= sizeof(real_tool_relative))
+        fail("tool path is too long");
+    join_path(real_tool, sizeof(real_tool), root, real_tool_relative);
+
+    char **loader_argv = calloc((size_t) argc + 6, sizeof(char *));
+    if (loader_argv == NULL) {
+        perror("embedded PostgreSQL launcher: calloc");
+        return 127;
+    }
+
+    loader_argv[0] = loader;
+    loader_argv[1] = "--library-path";
+    loader_argv[2] = library_path;
+    loader_argv[3] = "--argv0";
+    loader_argv[4] = executable;
+    loader_argv[5] = real_tool;
+    for (int index = 1; index < argc; index++)
+        loader_argv[index + 5] = argv[index];
+
+    execv(loader, loader_argv);
+    fprintf(
+        stderr,
+        "embedded PostgreSQL launcher: cannot execute %s: %s\n",
+        real_tool,
+        strerror(errno)
+    );
+    return 127;
+}