split_for_sort: Append mode implemented

There may be situations when not every input file is available at once,
so those can't be handled in a single session. The append mode opens the
files without overwriting the previous content so making the way the
tool can be used in scripts more flexible.

1 files changed, 54 insertions, 16 deletions

diff --git a/src/split_for_sort.c b/src/split_for_sort.c
index 0dd8e32..5678f6d 100644
--- a/src/split_for_sort.c
+++ b/src/split_for_sort.c
@@ -10,6 +10,7 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 #include <string.h>
 #include <ctype.h>
 #include <errno.h>
@@ -38,6 +39,9 @@ struct list_head {
     size_t length;
 };
 
+
+/* DECLARATIONS */
+
 int push_into_list_unique(struct list_head *list, char *name);
 int split_into_files(struct list_head *list, char *inputfile, char *prefix);
 size_t list_check_length(struct list_head *list);
@@ -45,12 +49,23 @@ struct list_head *extend_list(struct list_head *list, size_t splitlength, char *
 struct list_node *get_node(struct list_head *list, char *name);
 void destroy_list(struct list_head *list);
 void fflush_list(struct list_head *list);
-void print_list(struct list_head *list, FILE *out);
 int set_nofile_limit_to_hard();
 
+#ifdef DEBUGBUILD
+void print_list(struct list_head *list, FILE *out);
+#endif
+
 
+/* GLOBAL VARIABLES */
+int option_append_mode = 0;
 
-int set_nofile_limit_to_hard() {
+
+/* IMPLEMENTATION */
+
+/* modern Linux distributions set the soft limit to 1024 file descriptors,
+ * this may not be sufficient, therefore increase to the hard limit.
+ * */
+inline int set_nofile_limit_to_hard() {
     struct rlimit lim;
     if (getrlimit(RLIMIT_NOFILE , &lim) != 0) {
         LOGERR("ERROR: Failed to get RLIMIT_NOFILE: %s (errno %d)\n",
@@ -67,7 +82,7 @@ int set_nofile_limit_to_hard() {
 }
 
 
-void destroy_list(struct list_head *list) {
+inline void destroy_list(struct list_head *list) {
     struct list_node *n = NULL, *b = NULL;
     if (list == NULL)
         return;
@@ -82,7 +97,8 @@ void destroy_list(struct list_head *list) {
     free(list);
 }
 
-void fflush_list(struct list_head *list) {
+
+inline void fflush_list(struct list_head *list) {
     struct list_node *n = NULL;
     if (list == NULL) return;
     n = list->first;
@@ -94,6 +110,8 @@ void fflush_list(struct list_head *list) {
     }
 }
 
+
+#ifdef DEBUGBUILD
 void print_list(struct list_head *list, FILE *out) {
     struct list_node *n = NULL;
     if (list == NULL)
@@ -107,6 +125,8 @@ void print_list(struct list_head *list, FILE *out) {
         n = n->next;
     }
 }
+#endif
+
 
 inline size_t list_check_length(struct list_head *list) {
     size_t l = 0;
@@ -124,6 +144,7 @@ inline size_t list_check_length(struct list_head *list) {
     return l;
 }
 
+
 inline int push_into_list_unique(struct list_head *list, char *name) {
     size_t name_length = 0;
     struct list_node *ptr = NULL, *tmp = NULL;
@@ -158,6 +179,7 @@ inline int push_into_list_unique(struct list_head *list, char *name) {
     return 0;
 }
 
+
 inline struct list_node *get_node(struct list_head *list, char *name) {
     struct list_node *n = NULL;
     if (list == NULL || name == NULL || name[0] == '\0') {
@@ -175,6 +197,7 @@ inline struct list_node *get_node(struct list_head *list, char *name) {
     return NULL;
 }
 
+
 /* Open the given file and extend / create a list of output filenames,
  * based on the read content.
  * splitlength - the length of a line considered regarding the comparision.
@@ -243,6 +266,7 @@ struct list_head *extend_list(struct list_head *list, size_t splitlength, char *
     return list;
 }
 
+
 /* Parse the inputfile and split it's content into the given list of targets
  * with the prefix for the name of the target.
  */
@@ -252,7 +276,6 @@ int split_into_files(struct list_head *list, char *inputfile, char *prefix) {
     size_t i = 0, len=0, sl = 0;
     struct list_node *node = NULL;
 
-
     if (inputfile == NULL || strlen(inputfile) == 0) {
         LOGERR("ERROR: no valid filename for input.\n");
         return -1;
@@ -319,7 +342,7 @@ int split_into_files(struct list_head *list, char *inputfile, char *prefix) {
             /* keep the file descriptors open across the input files to be split */
             if (node->fd == NULL) {
                 snprintf(filename, BUFFERSIZE, "%s%s", ((prefix==NULL)?"":prefix), node->name);
-                if ((node->fd = fopen(filename, "w")) == NULL) {
+                if ((node->fd = fopen(filename, (option_append_mode)?"a":"w")) == NULL) {
                     LOGERR("ERROR: Failed to open file '%s': %s\n", filename, strerror(errno));
                     free(line);
                     free(line_head);
@@ -350,33 +373,48 @@ int split_into_files(struct list_head *list, char *inputfile, char *prefix) {
     return 0;
 }
 
+
 int main(int argc, char **argv) {
-    int i = 3;
+    int data_index = 2, length_index = 1, opt = 0, output_index = 0;
     size_t splitlength = 0;
     struct list_head *list = NULL;
 
     if (argc < 4) {
-        fprintf(stderr, "Usage: %s prefix length files...\n\n", argv[0]);
-        fprintf(stderr, "\tprefix - used with the output filenames\n"
+        fprintf(stderr, "Usage: %s prefix length files...\n", argv[0]);
+        fprintf(stderr, "or     %s -a prefix length files...\n\n", argv[0]);
+        fprintf(stderr, "-a       - don't overwrite existing files, instead append to those\n"
+                        "\tprefix - used with the output filenames\n"
                         "\tlength - the number of characters relevant for comparing\n");
         return EXIT_FAILURE;
     }
 
-    /* modern Linux distributions set the soft limit to 1024 file descriptors,
-     * this may not be sufficient, therefore increase to the hard limit  */
     set_nofile_limit_to_hard();
 
-    splitlength = strtoull(argv[2], NULL, 10);
+    while ((opt = getopt(argc, argv, "a")) != -1) {
+        switch (opt) {
+            case 'a':
+                option_append_mode = 1;
+                break;
+            default:
+                break;
+        };
+    }
+
+    data_index   += optind;
+    length_index += optind;
+    output_index += optind;
+
+    splitlength = strtoull(argv[length_index], NULL, 10);
     if (splitlength == 0) {
-        LOGERR("ERROR: Failed to read valid length from argument '%s' base 10 number >=1 expected\n", argv[2]);
+        LOGERR("ERROR: Failed to read valid length from argument '%s' base 10 number >=1 expected\n", argv[length_index]);
         return EXIT_FAILURE;
     }
 
-    for (i=3; i<argc; i++) {
+    for (; data_index<argc; data_index++) {
 //        fprintf(stderr, "=> Scan '%s' for bucket filenames\n", argv[i]);
-        list = extend_list(list, splitlength, argv[i]);
+        list = extend_list(list, splitlength, argv[data_index]);
 //        fprintf(stderr,"=> Split '%s' into bucket files\n", argv[i]);
-        if (split_into_files(list, argv[i], argv[1]) < 0) {
+        if (split_into_files(list, argv[data_index], argv[output_index]) < 0) {
             destroy_list(list);
             return EXIT_FAILURE;
         }