Commit 857c1d4ff2

@@ -983,7 +983,7 @@ fn detectAbiAndDynamicLinker(
 
     // Best case scenario: the executable is dynamically linked, and we can iterate
     // over our own shared objects and find a dynamic linker.
-    const elf_file = blk: {
+    const elf_file = elf_file: {
         // This block looks for a shebang line in /usr/bin/env,
         // if it finds one, then instead of using /usr/bin/env as the ELF file to examine, it uses the file it references instead,
         // doing the same logic recursively in case it finds another shebang line.
@@ -995,9 +995,22 @@ fn detectAbiAndDynamicLinker(
             // Haiku does not have a /usr root directory.
             .haiku => "/bin/env",
         };
-        // #! (2) + 255 (max length of shebang line since Linux 5.1) + \n (1)
-        var buffer: [258]u8 = undefined;
+
+        // According to `man 2 execve`:
+        //
+        // The kernel imposes a maximum length on the text
+        // that follows the "#!" characters at the start of a script;
+        // characters beyond the limit are ignored.
+        // Before Linux 5.1, the limit is 127 characters.
+        // Since Linux 5.1, the limit is 255 characters.
+        //
+        // Tests show that bash and zsh consider 255 as total limit,
+        // *including* "#!" characters and ignoring newline.
+        // For safety, we set max length as 255 + \n (1).
+        var buffer: [255 + 1]u8 = undefined;
         while (true) {
+            // Interpreter path can be relative on Linux, but
+            // for simplicity we are asserting it is an absolute path.
             const file = fs.openFileAbsolute(file_name, .{}) catch |err| switch (err) {
                 error.NoSpaceLeft => unreachable,
                 error.NameTooLong => unreachable,
@@ -1027,27 +1040,55 @@ fn detectAbiAndDynamicLinker(
 
                 else => |e| return e,
             };
-            errdefer file.close();
-
-            const len = preadAtLeast(file, &buffer, 0, buffer.len) catch |err| switch (err) {
+            var is_elf_file = false;
+            defer if (is_elf_file == false) file.close();
+
+            // Shortest working interpreter path is "#!/i" (4)
+            // (interpreter is "/i", assuming all pathes are absolute, like in above comment).
+            // ELF magic number length is also 4.
+            //
+            // If file is shorter than that, it is definitely not ELF file
+            // nor file with "shebang" line.
+            const min_len: usize = 4;
+
+            const len = preadAtLeast(file, &buffer, 0, min_len) catch |err| switch (err) {
                 error.UnexpectedEndOfFile,
                 error.UnableToReadElfFile,
-                => break :blk file,
+                => return defaultAbiAndDynamicLinker(cpu, os, query),
 
                 else => |e| return e,
             };
-            const newline = mem.indexOfScalar(u8, buffer[0..len], '\n') orelse break :blk file;
-            const line = buffer[0..newline];
-            if (!mem.startsWith(u8, line, "#!")) break :blk file;
-            var it = mem.tokenizeScalar(u8, line[2..], ' ');
-            file_name = it.next() orelse return defaultAbiAndDynamicLinker(cpu, os, query);
-            file.close();
+            const content = buffer[0..len];
+
+            if (mem.eql(u8, content[0..4], std.elf.MAGIC)) {
+                // It is very likely ELF file!
+                is_elf_file = true;
+                break :elf_file file;
+            } else if (mem.eql(u8, content[0..2], "#!")) {
+                // We detected shebang, now parse entire line.
+
+                // Trim leading "#!", spaces and tabs.
+                const trimmed_line = mem.trimLeft(u8, content[2..], &.{ ' ', '\t' });
+
+                // This line can have:
+                // * Interpreter path only,
+                // * Interpreter path and arguments, all separated by space, tab or NUL character.
+                // And optionally newline at the end.
+                const path_maybe_args = mem.trimRight(u8, trimmed_line, "\n");
+
+                // Separate path and args.
+                const path_end = mem.indexOfAny(u8, path_maybe_args, &.{ ' ', '\t', 0 }) orelse path_maybe_args.len;
+
+                file_name = path_maybe_args[0..path_end];
+                continue;
+            } else {
+                // Not a ELF file, not a shell script with "shebang line", invalid duck.
+                return defaultAbiAndDynamicLinker(cpu, os, query);
+            }
         }
     };
     defer elf_file.close();
 
-    // If Zig is statically linked, such as via distributed binary static builds, the above
-    // trick (block self_exe) won't work. The next thing we fall back to is the same thing, but for elf_file.
     // TODO: inline this function and combine the buffer we already read above to find
     // the possible shebang line with the buffer we use for the ELF header.
     return abiAndDynamicLinkerFromFile(elf_file, cpu, os, ld_info_list, query) catch |err| switch (err) {
@@ -1075,7 +1116,7 @@ fn detectAbiAndDynamicLinker(
     };
 }
 
-fn defaultAbiAndDynamicLinker(cpu: Target.Cpu, os: Target.Os, query: Target.Query) !Target {
+fn defaultAbiAndDynamicLinker(cpu: Target.Cpu, os: Target.Os, query: Target.Query) Target {
     const abi = query.abi orelse Target.Abi.default(cpu.arch, os);
     return .{
         .cpu = cpu,