reader parallel 3 with errors

.gitignore

@@ -31,6 +31,9 @@
 # Project Specific Files
 *.txt
 
+# Finals folder (for compressed work or binaries)
+finals
+
 # temporary save files
 *.swp
 
@@ -45,4 +48,4 @@ src/writer
 src/writer_parent
 src/reader_parent_1
 src/reader_parent_2
-
+src/reader_parent_3

src/reader.c

@@ -1,93 +1,112 @@
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 #include <sys/file.h>
 #include <errno.h>
+#include <sys/types.h> // for lseek()
+#include <unistd.h>    // for lseek()
+
 
 #include "reader.h"
 #include "shared_stuff.h"
 #include "reader_constants.h"
 
 static const int reader_f_flags = O_RDONLY;
 
+int reader(int file_num) {
+	return reader_ranged(file_num, 0, LINES_PER_FILE - 1);
+}
 
-int reader(int file_num){
-    char file_name[64];
-    int fd, file_value;
-    sprintf(file_name, FILENAME, file_num); // place file_num in FILENAME
-
-    fd = open(file_name, reader_f_flags);
-    if (fd == -1) { // error opening the file (does not exist?)
-        printf("open(%s) failed. errno=%d\n", file_name, errno);
-        return FILE_IS_INVALID;
-    }
-
+int reader_ranged(int file_num, int first_line, int last_line) {
+	char file_name[64];
+	int fd, file_value;
+	sprintf(file_name, FILENAME, file_num); // place file_num in FILENAME
+	
+	fd = open(file_name, reader_f_flags);
+	if (fd == -1) { // error opening the file (does not exist?)
+		printf("open(%s) failed. errno=%d\n", file_name, errno);
+		return FILE_IS_INVALID;
+	}  
+	
 	flock(fd, LOCK_SH);
-
-    if ( file_contents_are_valid(fd, WRITER_STRING_LEN, LINES_PER_FILE) == TRUE ){
-        file_value = FILE_IS_VALID;
-    } else{
-        file_value =  FILE_IS_INVALID;
-    }
-
+
+	if ( file_contents_are_valid(fd, WRITER_STRING_LEN,
+								 first_line, last_line) == TRUE ) {
+		file_value = FILE_IS_VALID;
+	} else {
+	    file_value =  FILE_IS_INVALID;
+	}
+
 	flock(fd, LOCK_UN);
-
-    close(fd);
-    return file_value;
+	
+	close(fd);
+	return file_value;
 }
 
 
-int file_contents_are_valid(int fd, int line_length, int line_count)
-{
-    // number of bytes to read at a time from the file
-    int line_size = line_length * sizeof(char);
-
-    char *first_line = (char*) malloc(line_size);
-
-    // try to read and validate the first line of the file
-    if ( read(fd, first_line, line_size) != line_size ) {
-        // the first line doesn't even have the correct number of characters
-        free(first_line);
-        return FALSE; // file is invalid
-    }
-    if ( !known_writer_string(first_line, line_length) ){
-        free(first_line);
-        return FALSE; // file is invalid
-    }
-
-    // the first line is valid, so we can compare it with all other lines
-    char *line_buffer = (char*) malloc(line_size);
-
-    // compare all lines with the first line
-    int i;
-    for ( i = 1 ; read(fd, line_buffer, line_size) == line_size; i++ )
-    {
-        if ( strncmp(line_buffer, first_line, line_length) != 0 || i >= line_count ){
-            free(first_line);
-            free(line_buffer);
-            return FALSE; // file is invalid
-        }
-    }
-
-    free(first_line);
-    free(line_buffer);
-
-    if (i != line_count)
-        return FALSE;
-
-    return TRUE; // file is valid
+int file_contents_are_valid(int fd, int line_length, int first_line, int last_line){
+	int line_count = last_line - first_line + 1;
+
+	// number of bytes to read at a time from the file
+	int line_size = line_length * sizeof(char);
+	DBG_PRINTF("fd=%d, line_size = %d\n", fd, line_size);
+
+	char *first_line_buf = (char*) malloc(line_size);
+
+	// try to read and validate the first line of the file
+	if ( read(fd, first_line_buf, line_size) != line_size ) {
+		// the first line doesn't even have the correct number of characters
+		free(first_line_buf);
+		DBG_PRINT("invalid file detected here\n");
+		return FALSE; // file is invalid
+	}
+
+	DBG_PRINTF("fd=%d, first_line_buf='%s'\n",fd,first_line_buf);
+	if ( !known_writer_string(first_line_buf, line_length) ){
+		free(first_line_buf);
+		DBG_PRINT("invalid file detected here\n");
+		return FALSE; // file is invalid
+	}
+
+	// the first line is valid, so we can compare it with all other lines
+	char *line_buffer = (char*) malloc(line_size);
+
+	lseek( fd, first_line * line_size, SEEK_SET );
+
+	// compare all lines with the first line
+	int i;
+	for ( i = 0 ; read(fd, line_buffer, line_size) == line_size; i++ )
+	{
+		if ( strncmp(line_buffer, first_line_buf, line_length) != 0 || i >= line_count ){
+			free(first_line_buf);
+			free(line_buffer);
+			DBG_PRINTF("fd=%d, invalid file detected here; first_line=%d, i=%d\nline_buff='%s'; first_line_buf='%s'\n",
+			            fd,first_line, i, line_buffer, first_line_buf);
+			return FALSE; // file is invalid
+		}
+	}
+
+	free(first_line_buf);
+	free(line_buffer);
+
+	if (i != line_count) {
+		DBG_PRINT("invalid file detected here\n");
+		return FALSE;
+	}
+
+	return TRUE; // file is valid
 }
 
 int known_writer_string(char *str, int str_len){
-    int i;
-
-    for ( i = 0; i < WRITER_STRING_COUNT; i++ ){
-        if ( strncmp(str, writer_strings[i], str_len) == 0 ){
-            return TRUE;
-        }
-    }
-
-    return FALSE;
+	int i;
+
+	for ( i = 0; i < WRITER_STRING_COUNT; i++ ){
+		if ( strncmp(str, writer_strings[i], str_len) == 0 ){
+			return TRUE;
+		}
+	}
+	DBG_PRINT("invalid file detected here\n");
+
+	return FALSE;
 }

src/reader.h

@@ -11,18 +11,30 @@
 	 */
 	int reader(int file_num);
 
+	/**
+	 * @brief Check the specified and limited file for consistency.
+	 * 
+	 * @param file_num The file number
+	 * @param first_line Line to start reading
+	 * @param last_line Line where reading ends
+	 * 
+	 * @retval FILE_IS_VALID or FILE_IS_INVALID
+	 */
+	int reader_ranged(int file_num, int first_line, int last_line);
+
 	/**
 	 * @brief Checks wether the file is valid.
 	 * A file is considered valid if it repeats one of the known writer strings
 	 * line_count times.
 	 * 
 	 * @param fd The file descriptor of the file to check
 	 * @param line_length Expected length of each line, in characters
-	 * @param line_count Expected number of lines in the file
+	 * @param first_line First line to start checking 
+	 * @param last_line Last line where checking ends
 	 * 
 	 * @retval TRUE if the file is valid; FALSE otherwise
 	 */
-	int file_contents_are_valid(int fd, int line_length, int line_count);
+	int file_contents_are_valid(int fd, int line_length, int first_line, int last_line);
 
 	/**
 	 * @brief looks for str in writer_strings

src/reader_constants.h

@@ -7,7 +7,7 @@
 	#define READER_2_THREAD_COUNT	3
 
 	/*	Constant K for Exercise 4 pdf	*/
-	#define READER_3_THREAD_COUNT	7	
+	#define READER_3_THREAD_COUNT	2	
 
 	#define FILE_IS_VALID	 0
 	#define FILE_IS_INVALID	-1

src/reader_parent_main_2.c

@@ -12,7 +12,7 @@ void *reader_thread(void *arg) {
     int file_num = *((int*) arg);
     int *ret = (int*) malloc( sizeof(int) );
 
-    if (ret == NULL)
+    if (ret == NULL || arg == NULL)
         exit(-1);
 
     *ret = reader(file_num);