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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /tools/perf/util/strbuf.h
Initial import
Diffstat (limited to 'tools/perf/util/strbuf.h')
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diff --git a/tools/perf/util/strbuf.h b/tools/perf/util/strbuf.h
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+#ifndef __PERF_STRBUF_H
+#define __PERF_STRBUF_H
+
+/*
+ * Strbuf's can be use in many ways: as a byte array, or to store arbitrary
+ * long, overflow safe strings.
+ *
+ * Strbufs has some invariants that are very important to keep in mind:
+ *
+ * 1. the ->buf member is always malloc-ed, hence strbuf's can be used to
+ * build complex strings/buffers whose final size isn't easily known.
+ *
+ * It is NOT legal to copy the ->buf pointer away.
+ * `strbuf_detach' is the operation that detachs a buffer from its shell
+ * while keeping the shell valid wrt its invariants.
+ *
+ * 2. the ->buf member is a byte array that has at least ->len + 1 bytes
+ * allocated. The extra byte is used to store a '\0', allowing the ->buf
+ * member to be a valid C-string. Every strbuf function ensure this
+ * invariant is preserved.
+ *
+ * Note that it is OK to "play" with the buffer directly if you work it
+ * that way:
+ *
+ * strbuf_grow(sb, SOME_SIZE);
+ * ... Here, the memory array starting at sb->buf, and of length
+ * ... strbuf_avail(sb) is all yours, and you are sure that
+ * ... strbuf_avail(sb) is at least SOME_SIZE.
+ * strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
+ *
+ * Of course, SOME_OTHER_SIZE must be smaller or equal to strbuf_avail(sb).
+ *
+ * Doing so is safe, though if it has to be done in many places, adding the
+ * missing API to the strbuf module is the way to go.
+ *
+ * XXX: do _not_ assume that the area that is yours is of size ->alloc - 1
+ * even if it's true in the current implementation. Alloc is somehow a
+ * "private" member that should not be messed with.
+ */
+
+#include <assert.h>
+
+extern char strbuf_slopbuf[];
+struct strbuf {
+ size_t alloc;
+ size_t len;
+ char *buf;
+};
+
+#define STRBUF_INIT { 0, 0, strbuf_slopbuf }
+
+/*----- strbuf life cycle -----*/
+extern void strbuf_init(struct strbuf *buf, ssize_t hint);
+extern void strbuf_release(struct strbuf *);
+extern char *strbuf_detach(struct strbuf *, size_t *);
+
+/*----- strbuf size related -----*/
+static inline ssize_t strbuf_avail(const struct strbuf *sb) {
+ return sb->alloc ? sb->alloc - sb->len - 1 : 0;
+}
+
+extern void strbuf_grow(struct strbuf *, size_t);
+
+static inline void strbuf_setlen(struct strbuf *sb, size_t len) {
+ if (!sb->alloc)
+ strbuf_grow(sb, 0);
+ assert(len < sb->alloc);
+ sb->len = len;
+ sb->buf[len] = '\0';
+}
+
+/*----- add data in your buffer -----*/
+static inline void strbuf_addch(struct strbuf *sb, int c) {
+ strbuf_grow(sb, 1);
+ sb->buf[sb->len++] = c;
+ sb->buf[sb->len] = '\0';
+}
+
+extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
+
+extern void strbuf_add(struct strbuf *, const void *, size_t);
+static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
+ strbuf_add(sb, s, strlen(s));
+}
+
+__attribute__((format(printf,2,3)))
+extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
+
+/* XXX: if read fails, any partial read is undone */
+extern ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint);
+
+#endif /* __PERF_STRBUF_H */