Initial implementation of file accessing using OS Module

integration_tests/run_tests.py

@@ -20,6 +20,7 @@
     "test_numpy_01.py",
     "test_numpy_02.py",
     "test_random.py",
+    "test_os.py",
     "test_builtin.py",
     "test_builtin_abs.py",
     "test_builtin_bool.py",

integration_tests/test_os.py

@@ -0,0 +1,14 @@
+from ltypes import i64
+from os import (open, read, close)
+
+def test():
+    path: str 
+    path = "integration_tests/test_os.py"
+    fd: i64
+    n: i64
+    fd = open(path, "r")
+    n = 100
+    print(read(fd, n))
+    close(fd) 
+
+test()

src/runtime/impure/lfortran_intrinsics.c

@@ -786,3 +786,38 @@ LFORTRAN_API void _lfortran_dp_rand_num(double *x) {
     srand(time(0));
     *x = rand() / (double) RAND_MAX;
 }
+
+LFORTRAN_API int64_t _lpython_open(char *path, char *flags)
+{
+    FILE *fd;
+    fd = fopen(path, flags);
+    if (!fd) 
+    {
+        printf("Error in opening the file!\n");
+        perror(path);
+        exit(1);
+    }
+    return (int64_t)fd;
+}
+
+LFORTRAN_API char* _lpython_read(int64_t fd, int64_t n)
+{
+    char *c = (char *) calloc(n, sizeof(char));
+    if (fd < 0) 
+    {
+        printf("Error in reading the file!\n");
+        exit(1);
+    }
+    int x = fread(c, 1, n, (FILE*)fd);
+    c[x] = '\0';
+    return c;
+}
+
+LFORTRAN_API void _lpython_close(int64_t fd)
+{
+    if (fclose((FILE*)fd) != 0) 
+    {
+        printf("Error in closing the file!\n");
+        exit(1);
+    }
+}

src/runtime/impure/lfortran_intrinsics.h

@@ -160,6 +160,9 @@ LFORTRAN_API void _lfortran_i64sys_clock(
         uint64_t *count, int64_t *rate, int64_t *max);
 LFORTRAN_API void _lfortran_sp_rand_num(float *x);
 LFORTRAN_API void _lfortran_dp_rand_num(double *x);
+LFORTRAN_API int64_t _lpython_open(char *path, char *flags);
+LFORTRAN_API char* _lpython_read(int64_t fd, int64_t n);
+LFORTRAN_API void _lpython_close(int64_t fd);
 
 #ifdef __cplusplus
 }

src/runtime/os.py

@@ -0,0 +1,32 @@
+from ltypes import i32, i64, ccall
+
+def open(path: str, flag: str) -> i64:
+    """
+    Returns the file descriptor for the newly opened file
+    """
+    return _lpython_open(path, flag)
+
+@ccall
+def _lpython_open(path: str, flag: str) -> i64:
+    pass
+
+def read(fd: i64, n: i64) -> str:
+    """
+    Reads at most `n` bytes from file descriptor
+    """
+    return _lpython_read(fd, n)
+
+@ccall
+def _lpython_read(fd: i64, n: i64) -> str:
+    pass
+
+def close(fd: i64):
+    """
+    Closes the file descriptor
+    """
+    _lpython_close(fd)
+    return
+
+@ccall
+def _lpython_close(fd: i64):
+    pass