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/*
* procfile is a library for reading kernel files from /proc
*
* The idea is this:
*
* - every file is opened once with procfile_open().
*
* - to read updated contents, we rewind it (lseek() to 0) and read again
* with procfile_readall().
*
* - for every file, we use a buffer that is adjusted to fit its entire
* contents in memory, allowing us to read it with a single read() call.
* (this provides atomicity / consistency on the data read from the kernel)
*
* - once the data are read, we update two arrays of pointers:
* - a words array, pointing to each word in the data read
* - a lines array, pointing to the first word for each line
*
* This is highly optimized. Both arrays are automatically adjusted to
* fit all contents and are updated in a single pass on the data:
* - a raspberry Pi can process 5.000+ files / sec.
* - a J1900 celeron processor can process 23.000+ files / sec.
*/
#ifndef NETDATA_PROCFILE_H
#define NETDATA_PROCFILE_H 1
// ----------------------------------------------------------------------------
// An array of words
typedef struct {
uint32_t len; // used entries
uint32_t size; // capacity
char *words[]; // array of pointers
} pfwords;
// ----------------------------------------------------------------------------
// An array of lines
typedef struct {
uint32_t words; // how many words this line has
uint32_t first; // the id of the first word of this line
// in the words array
} ffline;
typedef struct {
uint32_t len; // used entries
uint32_t size; // capacity
ffline lines[]; // array of lines
} pflines;
// ----------------------------------------------------------------------------
// The procfile
#define PROCFILE_FLAG_DEFAULT 0x00000000
#define PROCFILE_FLAG_NO_ERROR_ON_FILE_IO 0x00000001
typedef struct {
char filename[FILENAME_MAX + 1];
uint32_t flags;
int fd; // the file desriptor
size_t len; // the bytes we have placed into data
size_t size; // the bytes we have allocated for data
pflines *lines;
pfwords *words;
char separators[256];
char data[]; // allocated buffer to keep file contents
} procfile;
// close the proc file and free all related memory
extern void procfile_close(procfile *ff);
// (re)read and parse the proc file
extern procfile *procfile_readall(procfile *ff);
// open a /proc or /sys file
extern procfile *procfile_open(const char *filename, const char *separators, uint32_t flags);
// re-open a file
// if separators == NULL, the last separators are used
extern procfile *procfile_reopen(procfile *ff, const char *filename, const char *separators, uint32_t flags);
// example walk-through a procfile parsed file
extern void procfile_print(procfile *ff);
// ----------------------------------------------------------------------------
// set this to 1, to have procfile adapt its initial buffer allocation to the max allocation used so far
extern int procfile_adaptive_initial_allocation;
// return the number of lines present
#define procfile_lines(ff) (ff->lines->len)
// return the number of words of the Nth line
#define procfile_linewords(ff, line) (((line) < procfile_lines(ff)) ? (ff)->lines->lines[(line)].words : 0)
// return the Nth word of the file, or empty string
#define procfile_word(ff, word) (((word) < (ff)->words->len) ? (ff)->words->words[(word)] : "")
// return the first word of the Nth line, or empty string
#define procfile_line(ff, line) (((line) < procfile_lines(ff)) ? procfile_word((ff), (ff)->lines->lines[(line)].first) : "")
// return the Nth word of the current line
#define procfile_lineword(ff, line, word) (((line) < procfile_lines(ff) && (word) < procfile_linewords(ff, (line))) ? procfile_word((ff), (ff)->lines->lines[(line)].first + word) : "")
#endif /* NETDATA_PROCFILE_H */
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