Let $tail and $head work with FIFOs again (was disabled by commit 41a7cffbe7 ), and fix memory bug when to_real_path is used in init_tailhead

src/common.c

@@ -38,6 +38,7 @@
 #include <pthread.h>
 #include <unistd.h>
 #include "diskio.h"
+#include <fcntl.h>
 
 /* check for OS and include appropriate headers */
 #if defined(__linux__)
@@ -111,6 +112,27 @@ void to_real_path(char *dest, const char *source)
 	}
 }
 
+int open_fifo(const char *file, int *reported)
+{
+	char path[DEFAULT_TEXT_BUFFER_SIZE];
+	int fd = 0;
+
+	to_real_path(path, file);
+	fd = open(file, O_RDONLY | O_NONBLOCK);
+
+	if (fd == -1) {
+		if (!reported || *reported == 0) {
+			ERR("can't open %s: %s", file, strerror(errno));
+			if (reported) {
+				*reported = 1;
+			}
+		}
+		return -1;
+	}
+
+	return fd;
+}
+
 FILE *open_file(const char *file, int *reported)
 {
 	char path[DEFAULT_TEXT_BUFFER_SIZE];
@@ -126,7 +148,7 @@ FILE *open_file(const char *file, int *reported)
 				*reported = 1;
 			}
 		}
-		return 0;
+		return NULL;
 	}
 
 	return fp;

src/common.h

@@ -32,7 +32,8 @@ double get_time(void);
  * DEFAULT_TEXT_BUFFER_SIZE.  It's similar to variable_substitute, except only
  * cheques for $HOME and ~/ in path */
 void to_real_path(char *dest, const char *source);
-FILE *open_file(const char *, int *);
+FILE *open_file(const char *file, int *reported);
+int open_fifo(const char *file, int *reported);
 void variable_substitute(const char *s, char *dest, unsigned int n);
 
 void format_seconds(char *buf, unsigned int n, long t);

src/tailhead.c

@@ -27,15 +27,37 @@
 
 #include "text_object.h"
 #include "logging.h"
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
 
 #define MAX_HEADTAIL_LINES 30
 #define DEFAULT_MAX_HEADTAIL_USES 2
 
+void tailstring(char *string, int endofstring, int wantedlines) {
+	int i, linescounted = 0;
+
+	string[endofstring] = 0;
+	if(endofstring > 0) {
+		if(string[endofstring-1] == '\n') {	//work with or without \n at end of file
+			string[endofstring-1] = 0;
+		}
+		for(i = endofstring - 1; i >= 0 && linescounted < wantedlines; i--) {
+			if(string[i] == '\n') {
+				linescounted++;
+			}
+		}
+		if(i > 0) {
+			strfold(string, i+2);
+		}
+	}
+}
+
 void init_tailhead(const char* type, const char* arg, struct text_object *obj, void* free_at_crash) {
 	unsigned int args;
 
 	if(arg) {
-		obj->data.headtail.logfile=malloc(strlen(arg));
+		obj->data.headtail.logfile=malloc(DEFAULT_TEXT_BUFFER_SIZE);
 		obj->data.headtail.max_uses = DEFAULT_MAX_HEADTAIL_USES;
 		args = sscanf(arg, "%s %d %d", obj->data.headtail.logfile, &obj->data.headtail.wantedlines, &obj->data.headtail.max_uses);
 		if(args == 2 || args == 3) {
@@ -61,45 +83,62 @@ void init_tailhead(const char* type, const char* arg, struct text_object *obj, v
 }
 
 void print_tailhead(const char* type, struct text_object *obj, char *p, int p_max_size) {
-	int i, endofstring = 0, linescounted = 0;
+	int fd, i, endofstring = 0, linescounted = 0;
 	FILE *fp;
+	struct stat st;
 
+	//empty the buffer and reset the counter if we used it the max number of times
 	if(obj->data.headtail.buffer && obj->data.headtail.current_use >= obj->data.headtail.max_uses - 1) {
 		free(obj->data.headtail.buffer);
 		obj->data.headtail.buffer = NULL;
 		obj->data.headtail.current_use = 0;
 	}
+	//use the buffer if possible
 	if(obj->data.headtail.buffer) {
 		strcpy(p, obj->data.headtail.buffer);
 		obj->data.headtail.current_use++;
-	}else{
-		fp = open_file(obj->data.headtail.logfile, &obj->a);
-		if(fp != NULL) {
-			if(strcmp(type,"head") == 0) {
-				for(i = 0; i < obj->data.headtail.wantedlines; i++) {
-					fgets(p + endofstring, p_max_size - endofstring, fp);
-					endofstring = strlen(p);
-				}
-			} else if(strcmp(type,"tail") == 0) {
-				fseek(fp, - p_max_size, SEEK_END);
-				fread(p, 1, p_max_size, fp);
-				p[p_max_size - 1] = 0;
-				if(p[strlen(p)-1] == '\n') {	//work with or without \n at end of file
-					p[strlen(p)-1] = 0;
-				}
-				for(i = strlen(p); i >= 0 && linescounted < obj->data.headtail.wantedlines; i--) {
-					if(p[i] == '\n') {
-						linescounted++;
+	}else{	//otherwise find the needed data
+		if(stat(obj->data.headtail.logfile, &st) == 0) {
+			if (S_ISFIFO(st.st_mode)) {
+				fd = open_fifo(obj->data.headtail.logfile, &obj->a);
+				if(fd != -1) {
+					if(strcmp(type, "head") == 0) {
+						for(i = 0; linescounted < obj->data.headtail.wantedlines; i++) {
+							read(fd, p + i, 1);
+							if(p[i] == '\n') {
+								linescounted++;
+							}
+						}
+						p[i] = 0;
+					} else if(strcmp(type, "tail") == 0) {
+						i = read(fd, p, p_max_size - 1);
+						tailstring(p, i, obj->data.headtail.wantedlines);
+					} else {
+						CRIT_ERR(NULL, NULL, "If you are seeing this then there is a bug in the code, report it !");
 					}
 				}
-				if(i > 0) {
-					strfold(p, i+2);
-				}
+				close(fd);
 			} else {
-				CRIT_ERR(NULL, NULL, "If you are seeing this then there is a bug in the code, report it !");
+				fp = open_file(obj->data.headtail.logfile, &obj->a);
+				if(fp != NULL) {
+					if(strcmp(type, "head") == 0) {
+						for(i = 0; i < obj->data.headtail.wantedlines; i++) {
+							fgets(p + endofstring, p_max_size - endofstring, fp);
+							endofstring = strlen(p);
+						}
+					} else if(strcmp(type, "tail") == 0) {
+						fseek(fp, - p_max_size, SEEK_END);
+						i = fread(p, 1, p_max_size - 1, fp);
+						tailstring(p, i, obj->data.headtail.wantedlines);
+					} else {
+						CRIT_ERR(NULL, NULL, "If you are seeing this then there is a bug in the code, report it !");
+					}
+					fclose(fp);
+				}
 			}
-			fclose(fp);
 			obj->data.headtail.buffer = strdup(p);
+		} else {
+			CRIT_ERR(NULL, NULL, "$%s can't find information about %s", type, obj->data.headtail.logfile);
 		}
 	}
 	return;