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Merge pull request #2707 from pi-hole/tweak/wait-for

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Tweak undocumented wait-for option subtly
This commit is contained in:
Dominik
2025-11-30 20:13:29 +01:00
committed by GitHub
parent b3b6b745b0 71aaab9832
commit 84847f3152
2 changed files with 57 additions and 36 deletions
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4
src/args.c
View File

@@ -707,8 +707,8 @@ void parse_args(int argc, char *argv[])
fprintf(stderr, "Error: Timeout must be a non-negative integer.\n");
exit(EXIT_FAILURE);
}
const long initial_filesize = (argc == 6) ? (long)atol(argv[5]) : 0;
if(initial_filesize < 0)
const long initial_filesize = (argc == 6) ? (long)atol(argv[5]) : -1;
if(argc == 5 && initial_filesize < 0)
{
fprintf(stderr, "Error: Optional initial file size must be a non-negative integer if specified.\n");
exit(EXIT_FAILURE);

89
src/config/inotify.c
View File

@@ -155,6 +155,41 @@ bool check_inotify_event(void)
return config_changed;
}
// Scan a FILE stream for a target substring appended since the last scan.
static bool scan_file(FILE *file, const char *string, long *last_size, size_t *len, char **line)
{
// File was modified, get new filesize
fseek(file, 0, SEEK_END);
const long newsize = ftell(file);
// If file has grown (or is larger than initial position), read new
// lines
if(newsize > *last_size)
{
// Seek to previous scan position
fseek(file, *last_size, SEEK_SET);
// Read new lines
bool found = false;
while(getline(line, len, file) != -1)
{
// Check for target string
log_debug(DEBUG_INOTIFY, "Read new line: \"%s\"", *line);
if(strstr(*line, string) != NULL)
{
found = true;
break;
}
}
if(found)
return true;
// Update last_size position
*last_size = ftell(file);
}
return false;
}
/**
* @brief Waits for a specific string to appear in a file, scanning the last N
* lines and monitoring for new content.
@@ -182,8 +217,8 @@ bool wait_for_string_in_file(const char *filename, const char *string, unsigned
return false;
}
// Get current file size if initial_filesize is 0
if (initial_filesize == 0)
// Get current file size if initial_filesize is < 0
if (initial_filesize < 0)
{
log_debug(DEBUG_INOTIFY, "Determining filesize at invocation time");
if(fseek(file, 0, SEEK_END) != 0)
@@ -197,6 +232,21 @@ bool wait_for_string_in_file(const char *filename, const char *string, unsigned
initial_filesize = ftell(file);
}
log_debug(DEBUG_INOTIFY, "Starting to read file %s from byte offset %ld", filename, initial_filesize);
// Perform initial read
size_t len = 0;
char *line = NULL;
bool found = false;
long scan_start = initial_filesize;
if(scan_file(file, string, &scan_start, &len, &line))
{
// String found in initial scan
log_info("Found string \"%s\" in file %s (initial scan)", string, filename);
if(line != NULL)
free(line);
fclose(file);
return true;
}
// Use inotify to wait for new lines appended to the file
// Create inotify instance (non-blocking)
@@ -218,12 +268,6 @@ bool wait_for_string_in_file(const char *filename, const char *string, unsigned
return false;
}
// Loop until timeout reached (25ms * 40 = 1s) or string found
size_t len = 0;
char *line = NULL;
bool found = false;
long scan_start = initial_filesize;
// Initialize time tracking
struct timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);
@@ -272,34 +316,11 @@ bool wait_for_string_in_file(const char *filename, const char *string, unsigned
clock_gettime(CLOCK_REALTIME, &now);
continue;
}
// File was modified, get new filesize
fseek(file, 0, SEEK_END);
const long newsize = ftell(file);
// If file has grown, read new lines
if(newsize > scan_start)
{
// Seek to previous scan position
fseek(file, scan_start, SEEK_SET);
// Read new lines
while(getline(&line, &len, file) != -1)
{
// Check for target string
log_debug(DEBUG_INOTIFY, "Read new line: \"%s\"", line);
if(strstr(line, string) != NULL)
{
found = true;
break;
}
}
if(found)
break;
// Update scan_start position
scan_start = ftell(file);
found = scan_file(file, string, &scan_start, &len, &line);
// Update current time
clock_gettime(CLOCK_REALTIME, &now);
}
// Update current time
clock_gettime(CLOCK_REALTIME, &now);
}
// Clean up