2 * procfile is a library for reading kernel files from /proc
6 * - every file is opened once with procfile_open().
8 * - to read updated contents, we rewind it (lseek() to 0) and read again
9 * with procfile_readall().
11 * - for every file, we use a buffer that is adjusted to fit its entire
12 * contents in memory, allowing us to read it with a single read() call.
13 * (this provides atomicity / consistency on the data read from the kernel)
15 * - once the data are read, we update two arrays of pointers:
16 * - a words array, pointing to each word in the data read
17 * - a lines array, pointing to the first word for each line
19 * This is highly optimized. Both arrays are automatically adjusted to
20 * fit all contents and are updated in a single pass on the data:
21 * - a raspberry Pi can process 5.000+ files / sec.
22 * - a J1900 celeron processor can process 23.000+ files / sec.
26 #ifndef NETDATA_PROCFILE_H
27 #define NETDATA_PROCFILE_H 1
29 // if enabled, procfile will output a lot of debug info
32 // ----------------------------------------------------------------------------
36 uint32_t len; // used entries
37 uint32_t size; // capacity
38 char *words[]; // array of pointers
42 // ----------------------------------------------------------------------------
46 uint32_t words; // how many words this line has
47 uint32_t first; // the id of the first word of this line
52 uint32_t len; // used entries
53 uint32_t size; // capacity
54 ffline lines[]; // array of lines
58 // ----------------------------------------------------------------------------
62 char filename[FILENAME_MAX + 1];
63 int fd; // the file desriptor
64 ssize_t len; // the bytes we have placed into data
65 ssize_t size; // the bytes we have allocated for data
69 char data[]; // allocated buffer to keep file contents
72 // close the proc file and free all related memory
73 extern void procfile_close(procfile *ff);
75 // (re)read and parse the proc file
76 extern procfile *procfile_readall(procfile *ff);
78 // open a /proc or /sys file
79 extern procfile *procfile_open(const char *filename, const char *separators);
81 // example walk-through a procfile parsed file
82 extern void procfile_print(procfile *ff);
84 // ----------------------------------------------------------------------------
86 // return the number of lines present
87 #define procfile_lines(ff) (ff->lines->len)
89 // return the number of words of the Nth line
90 #define procfile_linewords(ff, line) (((line) < procfile_lines(ff)) ? (ff)->lines->lines[(line)].words : 0)
92 // return the Nth word of the file, or empty string
93 #define procfile_word(ff, word) (((word) < (ff)->words->len) ? (ff)->words->words[(word)] : "")
95 // return the first word of the Nth line, or empty string
96 #define procfile_line(ff, line) (((line) < procfile_lines(ff)) ? procfile_word((ff), (ff)->lines->lines[(line)].first) : "")
98 // return the Nth word of the current line
99 #define procfile_lineword(ff, line, word) (((line) < procfile_lines(ff) && (word) < procfile_linewords(ff, (line))) ? procfile_word((ff), (ff)->lines->lines[(line)].first + word) : "")
101 #endif /* NETDATA_PROCFILE_H */