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fix(stdlib_system): use STARTUPINFO for windows stdin redirection #1079

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Merged
jvdp1 merged 2 commits into from
Jan 4, 2026
+79 −37
Merged

fix(stdlib_system): use STARTUPINFO for windows stdin redirection #1079

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dfa495a
fix(stdlib_system): use STARTUPINFO for windows stdin redirection
JAi-SATHVIK Dec 29, 2025
d2fdd50
fix(stdlib_system): fix Windows stdin redirection, inheritance, and l…
JAi-SATHVIK Jan 1, 2026
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32 changes: 23 additions & 9 deletions src/stdlib_system_subprocess.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ void process_create_windows(const char* cmd, const char* stdin_stream,

STARTUPINFO si;
PROCESS_INFORMATION pi;
HANDLE hStdout = NULL, hStderr = NULL;
HANDLE hStdout = NULL, hStderr = NULL, hStdin = NULL;
SECURITY_ATTRIBUTES sa = { sizeof(SECURITY_ATTRIBUTES), NULL, TRUE };
FILE* stdin_fp = NULL;

Expand All @@ -58,6 +58,23 @@ void process_create_windows(const char* cmd, const char* stdin_stream,
fclose(stdin_fp);
}

// Open stdin file if provided, otherwise use the null device
if (stdin_file) {
hStdin = CreateFile(stdin_file, GENERIC_READ, 0, &sa, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if (hStdin == INVALID_HANDLE_VALUE) {
fprintf(stderr, "Failed to open stdin file for reading\n");
return;
}
} else {
hStdin = CreateFile("NUL", GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if (hStdin == INVALID_HANDLE_VALUE) {
fprintf(stderr, "Failed to open null device for stdin\n");
return;
}
}
si.hStdInput = hStdin;
si.dwFlags |= STARTF_USESTDHANDLES;

// Open stdout file if provided, otherwise use the null device
if (stdout_file) {
hStdout = CreateFile(stdout_file, GENERIC_WRITE, 0, &sa, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
Expand Down Expand Up @@ -92,23 +109,19 @@ void process_create_windows(const char* cmd, const char* stdin_stream,
si.hStdError = hStderr;
si.dwFlags |= STARTF_USESTDHANDLES;

// Prepare the command line with redirected stdin
// Prepare the command line
char* full_cmd;
size_t cmd_len = strlen(cmd);
size_t stdin_len = stdin_file ? strlen(stdin_file) : 0;
size_t full_cmd_len = cmd_len + stdin_len + 5;
size_t full_cmd_len = cmd_len + 1;
full_cmd = (char*)malloc(full_cmd_len);
if (!full_cmd) {
fprintf(stderr, "Failed to allocate memory for full_cmd\n");
return;
}

// Use full_cmd as needed (e.g., pass to CreateProcess)
if (stdin_file) {
snprintf(full_cmd, full_cmd_len, "%s < %s", cmd, stdin_file);
} else {
snprintf(full_cmd, full_cmd_len, "%s", cmd);
}
snprintf(full_cmd, full_cmd_len, "%s", cmd);


// Create the process
BOOL success = CreateProcess(
Expand All @@ -133,6 +146,7 @@ void process_create_windows(const char* cmd, const char* stdin_stream,
}

// Close unneeded handles
if (hStdin) CloseHandle(hStdin);
if (hStdout) CloseHandle(hStdout);
if (hStderr) CloseHandle(hStderr);

Expand Down
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