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![Tzvetomir Stoyanov](/assets/img/avatar_default.png)
In order to make libtraceevent into a proper library, its API should be straightforward. The trace_seq_printf() and trace_seq_vprintf() APIs have inconsistent returned values with the other trace_seq_* APIs. This path changes the return logic of trace_seq_printf() and trace_seq_vprintf() to return the number of printed characters, as the other trace_seq_* related APIs. Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20181201040852.485792891@goodmis.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
249 lines
5.4 KiB
C
249 lines
5.4 KiB
C
// SPDX-License-Identifier: LGPL-2.1
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/*
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* Copyright (C) 2009 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
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*
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*/
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#include "trace-seq.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdarg.h>
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#include <asm/bug.h>
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#include "event-parse.h"
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#include "event-utils.h"
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/*
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* The TRACE_SEQ_POISON is to catch the use of using
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* a trace_seq structure after it was destroyed.
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*/
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#define TRACE_SEQ_POISON ((void *)0xdeadbeef)
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#define TRACE_SEQ_CHECK(s) \
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do { \
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if (WARN_ONCE((s)->buffer == TRACE_SEQ_POISON, \
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"Usage of trace_seq after it was destroyed")) \
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(s)->state = TRACE_SEQ__BUFFER_POISONED; \
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} while (0)
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#define TRACE_SEQ_CHECK_RET_N(s, n) \
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do { \
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TRACE_SEQ_CHECK(s); \
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if ((s)->state != TRACE_SEQ__GOOD) \
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return n; \
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} while (0)
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#define TRACE_SEQ_CHECK_RET(s) TRACE_SEQ_CHECK_RET_N(s, )
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#define TRACE_SEQ_CHECK_RET0(s) TRACE_SEQ_CHECK_RET_N(s, 0)
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/**
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* trace_seq_init - initialize the trace_seq structure
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* @s: a pointer to the trace_seq structure to initialize
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*/
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void trace_seq_init(struct trace_seq *s)
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{
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s->len = 0;
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s->readpos = 0;
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s->buffer_size = TRACE_SEQ_BUF_SIZE;
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s->buffer = malloc(s->buffer_size);
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if (s->buffer != NULL)
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s->state = TRACE_SEQ__GOOD;
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else
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s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
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}
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/**
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* trace_seq_reset - re-initialize the trace_seq structure
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* @s: a pointer to the trace_seq structure to reset
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*/
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void trace_seq_reset(struct trace_seq *s)
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{
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if (!s)
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return;
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TRACE_SEQ_CHECK(s);
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s->len = 0;
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s->readpos = 0;
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}
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/**
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* trace_seq_destroy - free up memory of a trace_seq
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* @s: a pointer to the trace_seq to free the buffer
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*
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* Only frees the buffer, not the trace_seq struct itself.
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*/
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void trace_seq_destroy(struct trace_seq *s)
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{
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if (!s)
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return;
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TRACE_SEQ_CHECK_RET(s);
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free(s->buffer);
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s->buffer = TRACE_SEQ_POISON;
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}
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static void expand_buffer(struct trace_seq *s)
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{
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char *buf;
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buf = realloc(s->buffer, s->buffer_size + TRACE_SEQ_BUF_SIZE);
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if (WARN_ONCE(!buf, "Can't allocate trace_seq buffer memory")) {
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s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
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return;
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}
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s->buffer = buf;
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s->buffer_size += TRACE_SEQ_BUF_SIZE;
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}
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/**
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* trace_seq_printf - sequence printing of trace information
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* @s: trace sequence descriptor
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* @fmt: printf format string
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*
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* It returns 0 if the trace oversizes the buffer's free
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* space, the number of characters printed, or a negative
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* value in case of an error.
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*
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* The tracer may use either sequence operations or its own
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* copy to user routines. To simplify formating of a trace
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* trace_seq_printf is used to store strings into a special
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* buffer (@s). Then the output may be either used by
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* the sequencer or pulled into another buffer.
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*/
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int
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trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
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{
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va_list ap;
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int len;
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int ret;
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try_again:
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TRACE_SEQ_CHECK_RET0(s);
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len = (s->buffer_size - 1) - s->len;
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va_start(ap, fmt);
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ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
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va_end(ap);
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if (ret >= len) {
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expand_buffer(s);
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goto try_again;
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}
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if (ret > 0)
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s->len += ret;
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return ret;
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}
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/**
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* trace_seq_vprintf - sequence printing of trace information
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* @s: trace sequence descriptor
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* @fmt: printf format string
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*
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* It returns 0 if the trace oversizes the buffer's free
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* space, the number of characters printed, or a negative
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* value in case of an error.
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* *
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* The tracer may use either sequence operations or its own
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* copy to user routines. To simplify formating of a trace
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* trace_seq_printf is used to store strings into a special
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* buffer (@s). Then the output may be either used by
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* the sequencer or pulled into another buffer.
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*/
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int
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trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
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{
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int len;
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int ret;
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try_again:
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TRACE_SEQ_CHECK_RET0(s);
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len = (s->buffer_size - 1) - s->len;
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ret = vsnprintf(s->buffer + s->len, len, fmt, args);
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if (ret >= len) {
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expand_buffer(s);
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goto try_again;
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}
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if (ret > 0)
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s->len += ret;
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return ret;
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}
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/**
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* trace_seq_puts - trace sequence printing of simple string
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* @s: trace sequence descriptor
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* @str: simple string to record
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*
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* The tracer may use either the sequence operations or its own
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* copy to user routines. This function records a simple string
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* into a special buffer (@s) for later retrieval by a sequencer
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* or other mechanism.
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*/
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int trace_seq_puts(struct trace_seq *s, const char *str)
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{
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int len;
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TRACE_SEQ_CHECK_RET0(s);
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len = strlen(str);
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while (len > ((s->buffer_size - 1) - s->len))
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expand_buffer(s);
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TRACE_SEQ_CHECK_RET0(s);
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memcpy(s->buffer + s->len, str, len);
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s->len += len;
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return len;
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}
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int trace_seq_putc(struct trace_seq *s, unsigned char c)
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{
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TRACE_SEQ_CHECK_RET0(s);
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while (s->len >= (s->buffer_size - 1))
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expand_buffer(s);
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TRACE_SEQ_CHECK_RET0(s);
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s->buffer[s->len++] = c;
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return 1;
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}
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void trace_seq_terminate(struct trace_seq *s)
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{
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TRACE_SEQ_CHECK_RET(s);
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/* There's always one character left on the buffer */
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s->buffer[s->len] = 0;
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}
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int trace_seq_do_fprintf(struct trace_seq *s, FILE *fp)
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{
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TRACE_SEQ_CHECK(s);
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switch (s->state) {
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case TRACE_SEQ__GOOD:
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return fprintf(fp, "%.*s", s->len, s->buffer);
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case TRACE_SEQ__BUFFER_POISONED:
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fprintf(fp, "%s\n", "Usage of trace_seq after it was destroyed");
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break;
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case TRACE_SEQ__MEM_ALLOC_FAILED:
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fprintf(fp, "%s\n", "Can't allocate trace_seq buffer memory");
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break;
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}
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return -1;
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}
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int trace_seq_do_printf(struct trace_seq *s)
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{
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return trace_seq_do_fprintf(s, stdout);
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}
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