1 files changed, 249 insertions, 0 deletions
diff --git a/src/trace-seq.c b/src/trace-seq.c
new file mode 100644
index 0000000..8d5ecd2
--- /dev/null
+++ b/src/trace-seq.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2009 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include "trace-seq.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+
+#include <asm/bug.h>
+#include "event-parse.h"
+#include "event-utils.h"
+
+/*
+ * The TRACE_SEQ_POISON is to catch the use of using
+ * a trace_seq structure after it was destroyed.
+ */
+#define TRACE_SEQ_POISON	((void *)0xdeadbeef)
+#define TRACE_SEQ_CHECK(s)						\
+do {									\
+	if (WARN_ONCE((s)->buffer == TRACE_SEQ_POISON,			\
+		      "Usage of trace_seq after it was destroyed"))	\
+		(s)->state = TRACE_SEQ__BUFFER_POISONED;		\
+} while (0)
+
+#define TRACE_SEQ_CHECK_RET_N(s, n)		\
+do {						\
+	TRACE_SEQ_CHECK(s);			\
+	if ((s)->state != TRACE_SEQ__GOOD)	\
+		return n; 			\
+} while (0)
+
+#define TRACE_SEQ_CHECK_RET(s)   TRACE_SEQ_CHECK_RET_N(s, )
+#define TRACE_SEQ_CHECK_RET0(s)  TRACE_SEQ_CHECK_RET_N(s, 0)
+
+/**
+ * trace_seq_init - initialize the trace_seq structure
+ * @s: a pointer to the trace_seq structure to initialize
+ */
+void trace_seq_init(struct trace_seq *s)
+{
+	s->len = 0;
+	s->readpos = 0;
+	s->buffer_size = TRACE_SEQ_BUF_SIZE;
+	s->buffer = malloc(s->buffer_size);
+	if (s->buffer != NULL)
+		s->state = TRACE_SEQ__GOOD;
+	else
+		s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
+}
+
+/**
+ * trace_seq_reset - re-initialize the trace_seq structure
+ * @s: a pointer to the trace_seq structure to reset
+ */
+void trace_seq_reset(struct trace_seq *s)
+{
+	if (!s)
+		return;
+	TRACE_SEQ_CHECK(s);
+	s->len = 0;
+	s->readpos = 0;
+}
+
+/**
+ * trace_seq_destroy - free up memory of a trace_seq
+ * @s: a pointer to the trace_seq to free the buffer
+ *
+ * Only frees the buffer, not the trace_seq struct itself.
+ */
+void trace_seq_destroy(struct trace_seq *s)
+{
+	if (!s)
+		return;
+	TRACE_SEQ_CHECK_RET(s);
+	free(s->buffer);
+	s->buffer = TRACE_SEQ_POISON;
+}
+
+static void expand_buffer(struct trace_seq *s)
+{
+	char *buf;
+
+	buf = realloc(s->buffer, s->buffer_size + TRACE_SEQ_BUF_SIZE);
+	if (WARN_ONCE(!buf, "Can't allocate trace_seq buffer memory")) {
+		s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
+		return;
+	}
+
+	s->buffer = buf;
+	s->buffer_size += TRACE_SEQ_BUF_SIZE;
+}
+
+/**
+ * trace_seq_printf - sequence printing of trace information
+ * @s: trace sequence descriptor
+ * @fmt: printf format string
+ *
+ * It returns 0 if the trace oversizes the buffer's free
+ * space, the number of characters printed, or a negative
+ * value in case of an error.
+ *
+ * The tracer may use either sequence operations or its own
+ * copy to user routines. To simplify formating of a trace
+ * trace_seq_printf is used to store strings into a special
+ * buffer (@s). Then the output may be either used by
+ * the sequencer or pulled into another buffer.
+ */
+int
+trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
+{
+	va_list ap;
+	int len;
+	int ret;
+
+ try_again:
+	TRACE_SEQ_CHECK_RET0(s);
+
+	len = (s->buffer_size - 1) - s->len;
+
+	va_start(ap, fmt);
+	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+	va_end(ap);
+
+	if (ret >= len) {
+		expand_buffer(s);
+		goto try_again;
+	}
+
+	if (ret > 0)
+		s->len += ret;
+
+	return ret;
+}
+
+/**
+ * trace_seq_vprintf - sequence printing of trace information
+ * @s: trace sequence descriptor
+ * @fmt: printf format string
+ *
+ * It returns 0 if the trace oversizes the buffer's free
+ * space, the number of characters printed, or a negative
+ * value in case of an error.
+ * *
+ * The tracer may use either sequence operations or its own
+ * copy to user routines. To simplify formating of a trace
+ * trace_seq_printf is used to store strings into a special
+ * buffer (@s). Then the output may be either used by
+ * the sequencer or pulled into another buffer.
+ */
+int
+trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
+{
+	int len;
+	int ret;
+
+ try_again:
+	TRACE_SEQ_CHECK_RET0(s);
+
+	len = (s->buffer_size - 1) - s->len;
+
+	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
+
+	if (ret >= len) {
+		expand_buffer(s);
+		goto try_again;
+	}
+
+	if (ret > 0)
+		s->len += ret;
+
+	return ret;
+}
+
+/**
+ * trace_seq_puts - trace sequence printing of simple string
+ * @s: trace sequence descriptor
+ * @str: simple string to record
+ *
+ * The tracer may use either the sequence operations or its own
+ * copy to user routines. This function records a simple string
+ * into a special buffer (@s) for later retrieval by a sequencer
+ * or other mechanism.
+ */
+int trace_seq_puts(struct trace_seq *s, const char *str)
+{
+	int len;
+
+	TRACE_SEQ_CHECK_RET0(s);
+
+	len = strlen(str);
+
+	while (len > ((s->buffer_size - 1) - s->len))
+		expand_buffer(s);
+
+	TRACE_SEQ_CHECK_RET0(s);
+
+	memcpy(s->buffer + s->len, str, len);
+	s->len += len;
+
+	return len;
+}
+
+int trace_seq_putc(struct trace_seq *s, unsigned char c)
+{
+	TRACE_SEQ_CHECK_RET0(s);
+
+	while (s->len >= (s->buffer_size - 1))
+		expand_buffer(s);
+
+	TRACE_SEQ_CHECK_RET0(s);
+
+	s->buffer[s->len++] = c;
+
+	return 1;
+}
+
+void trace_seq_terminate(struct trace_seq *s)
+{
+	TRACE_SEQ_CHECK_RET(s);
+
+	/* There's always one character left on the buffer */
+	s->buffer[s->len] = 0;
+}
+
+int trace_seq_do_fprintf(struct trace_seq *s, FILE *fp)
+{
+	TRACE_SEQ_CHECK(s);
+
+	switch (s->state) {
+	case TRACE_SEQ__GOOD:
+		return fprintf(fp, "%.*s", s->len, s->buffer);
+	case TRACE_SEQ__BUFFER_POISONED:
+		fprintf(fp, "%s\n", "Usage of trace_seq after it was destroyed");
+		break;
+	case TRACE_SEQ__MEM_ALLOC_FAILED:
+		fprintf(fp, "%s\n", "Can't allocate trace_seq buffer memory");
+		break;
+	}
+	return -1;
+}
+
+int trace_seq_do_printf(struct trace_seq *s)
+{
+	return trace_seq_do_fprintf(s, stdout);
+}