Some more string utils and doc updates

Author: sidcha

src/procutils.c

@@ -4,6 +4,11 @@
  * SPDX-License-Identifier: MIT
  */
 
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+
 #include "procutils.h"
 
 int read_pid(const char *file, int *pid)
@@ -44,21 +49,40 @@ int write_pid(const char *file)
 	return 0;
 }
 
-int redirect_output_to_log_file(const char *file)
+int o_redirect(int mode, const char *file)
 {
-	int log_file = open(file, O_RDWR | O_CREAT | O_APPEND, 0600);
+	int fd = -1;
+	int has_err = 0;
 
-	if (log_file == -1) {
-		perror("opening log_file");
-		return -1;
+	if (file != NULL) {
+		fd = open(file, O_RDWR | O_CREAT | O_APPEND, 0644);
+		if (fd == -1) {
+			perror("opening log_file");
+			return -1;
+		}
 	}
-	if (dup2(log_file, fileno(stdout)) == -1) {
-		perror("cannot redirect stdout to log_file");
-		return -1;
+
+	if (mode & 0x01) {
+		if (fd != -1) {
+			if (dup2(fd, fileno(stdout)) == -1) {
+				perror("cannot redirect stdout to log_file");
+				has_err = -1;
+			}
+		} else {
+			close(fileno(stdout));
+		}
 	}
-	if (dup2(log_file, fileno(stderr)) == -1) {
-		perror("cannot redirect stderr to log_file");
-		return -1;
+
+	if (mode & 0x02) {
+		if (fd != -1) {
+			if (dup2(fd, fileno(stderr)) == -1) {
+				perror("cannot redirect stderr to log_file");
+				has_err = -1;
+			}
+		} else {
+			close(fileno(stderr));
+		}
 	}
-	return 0;
+
+	return has_err;
 }

src/procutils.h

@@ -1,11 +1,40 @@
 #ifndef _UTIL_PROCUTILS_H_
 #define _UTIL_PROCUTILS_H_
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
+/*
+ * read_pid() - Reads PID from `file`. The file's content must just be
+ * be PID number, as written by a call to write_pid(). On success, copies
+ * the PID read from file into `pid`.
+ *
+ * Returns:
+ *  0 - Success
+ * -1 - Failure
+ */
+int read_pid(const char *file, int *pid);
 
+/*
+ * write_pid() - Writes the calling process's PID to the file specified.
+ *
+ * Returns:
+ *  0 - Success
+ * -1 - Failure
+ */
+int write_pid(const char *file);
 
+/*
+ * o_redirect() - Redirects stdout/stderr to file specified.
+ *
+ * Params:
+ *   mode - Bit mask.
+ *           bit-0: STDOUT
+ *           bit-1: STDERR
+ *   file - Path to log file. if null, close() is called on the
+ *          corresponding FDs (from mode above).
+ *  Examples:
+ *    o_redirect(1, "/tmp/my_log.txt"); // redirects stdout to "/tmp/my_log.txt"
+ *    o_redirect(3, "/tmp/my_log.txt"); // Same as above; but redirects stdout and strerr
+ *    o_redirect(3, NULL); // close both stdout and strerr. Same as `> /dev/null 1>&2`
+ */
+int o_redirect(int mode, const char *file);
 
 #endif /* _UTIL_PROCUTILS_H_ */

src/strlib.c

@@ -43,4 +43,3 @@ int str_copy(string_t *s, const char *mode, const char *str, size_t len)
 	s->buf[s->len] = 0;
 	return len;
 }
-

src/strlib.h

@@ -83,7 +83,7 @@ int str_printf(string_t *s, const char *mode, const char *fmt, ...);
  * 	Use `mode` as defined above in "String Ops Modes" section.
  *
  * Example:
- * 	str_copyf(&my_string, "c", "Hello", 5);
+ * 	str_copy(&my_string, "c", "Hello", 5);
  * 	// now, my_string == "Hello"
  * 	str_copy(&my_string, "a", " World", 6);
  * 	// now, my_string == "Hello World"

src/strutils.c

@@ -67,6 +67,13 @@ int safe_atoi(const char *a, int *i)
 	return 0;
 }
 
+char *safe_strncpy(char* dest, const char* src, size_t size)
+{
+    strncpy(dest, src, size - 1);
+    dest[size - 1] = '\0';
+    return dest;
+}
+
 int trim_suffix(char *str, const char *suffix)
 {
 	int i, j;
@@ -84,5 +91,36 @@ int trim_suffix(char *str, const char *suffix)
 		i--; j--;
 	}
 
-	return str[i] = 0;
+	return str[i] = '\0';
+}
+
+void rstrip(char *str)
+{
+	int i;
+
+	i = strlen(str);
+	while (str[--i] == ' ')
+		str[i] = '\0';
+}
+
+void lstrip(char *str)
+{
+	int i = 0, j = 0;
+
+	while (str[i] && str[i] == ' ')
+		i++;
+
+	while (i && str[i]) {
+		str[j] = str[i];
+		i++; j++;
+	}
+
+	if (j != 0)
+		str[j] = '\0';
+}
+
+void strip(char *str)
+{
+	lstrip(str);
+	rstrip(str);
 }

src/strutils.h

@@ -11,7 +11,8 @@
 #include <string.h>
 
 /*
- * atohstr - Array to Hex String
+ * atohstr() - Converts an array of bytes to its hexadecimal string
+ * representation.
  *
  * Usage:
  *   uint8_t arr[4] = { 0xca, 0xfe, 0xba, 0xbe };
@@ -21,12 +22,13 @@
  *   }
  *
  * Note:
- * The passed char *hstr, has to be 2 * arr_len.
+ * sizeof passed char *hstr, has to be atleast (2 * arr_len) + 1.
  */
 int atohstr(char *hstr, const uint8_t *arr, const int arr_len);
 
 /*
- * hstrtoa - Hex String to Array
+ * hstrtoa() - Converts a hexadecimal string to it's value as array of
+ * bytes.
  *
  * Usage:
  *   uint8_t arr[4];
@@ -36,10 +38,30 @@ int atohstr(char *hstr, const uint8_t *arr, const int arr_len);
  *   }
  *
  * Note:
- * uint8_t *arr has to be atleast half of strlen(hstr)
+ * sizeof uint8_t *arr has to be atleast half of strlen(hstr)
  */
 int hstrtoa(uint8_t *arr, const char *hstr);
 
+/*
+ * safe_atoi() - A wrapper for atoi() that returns -ve on non number-ish
+ * strings. This can be used to distinguish "0" from "A" as both would
+ * return 0 by the bare atoi()'s contract.
+ */
 int safe_atoi(const char *a, int *i);
 
+/*
+ * safe_strncpy() - A wrapper for strnlen() that guarantees null
+ * terminated copy to dest. If strlen(src) > size, then only size-1
+ * chars are copied to dest and a terminating '\0' is added.
+ */
+char *safe_strncpy(char* dest, const char* src, size_t size);
+
+/*
+ * rstrip(), lstrip(), strip() - String space trim methods, as defined
+ * in python3 programming language.
+ */
+void rstrip(char *str);
+void lstrip(char *str);
+void strip(char *str);
+
 #endif /* _UTIL_STRUTIL_H_ */