diff options
| -rw-r--r-- | Makefile | 8 | ||||
| -rw-r--r-- | lineread.c | 115 | ||||
| -rw-r--r-- | lineread.h | 31 |
3 files changed, 150 insertions, 4 deletions
@@ -32,16 +32,16 @@ CFLAGS += -DRLIMIT_STACK_VAL=$(RLIMIT_STACK_VAL) CFLAGS += -DARCH=\"$(TARGET_ARCH)\" PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c icmp.c igmp.c \ - mld.c ndp.c netlink.c packet.c passt.c pasta.c pcap.c siphash.c \ - tap.c tcp.c tcp_splice.c udp.c util.c + lineread.c mld.c ndp.c netlink.c packet.c passt.c pasta.c pcap.c \ + siphash.c tap.c tcp.c tcp_splice.c udp.c util.c QRAP_SRCS = qrap.c SRCS = $(PASST_SRCS) $(QRAP_SRCS) MANPAGES = passt.1 pasta.1 qrap.1 PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h icmp.h \ - ndp.h netlink.h packet.h passt.h pasta.h pcap.h siphash.h \ - tap.h tcp.h tcp_splice.h udp.h util.h + lineread.h ndp.h netlink.h packet.h passt.h pasta.h pcap.h \ + siphash.h tap.h tcp.h tcp_splice.h udp.h util.h HEADERS = $(PASST_HEADERS) # On gcc 11.2, with -O2 and -flto, tcp_hash() and siphash_20b(), if inlined, diff --git a/lineread.c b/lineread.c new file mode 100644 index 0000000..59021e6 --- /dev/null +++ b/lineread.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: AGPL-3.0-or-later + +/* PASST - Plug A Simple Socket Transport + * for qemu/UNIX domain socket mode + * + * PASTA - Pack A Subtle Tap Abstraction + * for network namespace/tap device mode + * + * lineread.c - Allocation free line-by-line buffered file input + * + * Copyright Red Hat + * Author: David Gibson <david@gibson.dropbear.id.au> + */ + +#include <stddef.h> +#include <fcntl.h> +#include <string.h> +#include <stdbool.h> +#include <assert.h> +#include <unistd.h> + +#include "lineread.h" + +/** + * lineread_init() - Prepare for line by line file reading without allocation + * @lr: Line reader state structure to initialize + * @fd: File descriptor to read lines from + */ +void lineread_init(struct lineread *lr, int fd) +{ + lr->fd = fd; + lr->next_line = lr->count = 0; +} + +/** + * peek_line() - Find and NULL-terminate next line in buffer + * @lr: Line reader state structure + * @eof: Caller indicates end-of-file was already found by read() + * + * Return: length of line in bytes, -1 if no line was found + */ +static int peek_line(struct lineread *lr, bool eof) +{ + char *nl; + + /* Sanity checks (which also document invariants) */ + assert(lr->count >= 0); + assert(lr->next_line >= 0); + assert(lr->next_line + lr->count >= lr->next_line); + assert(lr->next_line + lr->count <= LINEREAD_BUFFER_SIZE); + + nl = memchr(lr->buf + lr->next_line, '\n', lr->count); + + if (nl) { + *nl = '\0'; + return nl - lr->buf - lr->next_line + 1; + } + + if (eof) { + lr->buf[lr->next_line + lr->count] = '\0'; + /* No trailing newline, so treat all remaining bytes + * as the last line + */ + return lr->count; + } + + return -1; +} + +/** + * lineread_get() - Read a single line from file (no allocation) + * @lr: Line reader state structure + * @line: Place a pointer to the next line in this variable + * + * Return: Length of line read on success, 0 on EOF, negative on error + */ +int lineread_get(struct lineread *lr, char **line) +{ + bool eof = false; + int line_len; + + while ((line_len = peek_line(lr, eof)) < 0) { + int rc; + + if ((lr->next_line + lr->count) == LINEREAD_BUFFER_SIZE) { + /* No space at end */ + if (lr->next_line == 0) { + /* Buffer is full, which means we've + * hit a line too long for us to + * process. FIXME: report error + * better + */ + return -1; + } + memmove(lr->buf, lr->buf + lr->next_line, lr->count); + lr->next_line = 0; + } + + /* Read more data into the end of buffer */ + rc = read(lr->fd, lr->buf + lr->next_line + lr->count, + LINEREAD_BUFFER_SIZE - lr->next_line - lr->count); + if (rc < 0) + return rc; + + if (rc == 0) + eof = true; + else + lr->count += rc; + } + + *line = lr->buf + lr->next_line; + lr->next_line += line_len; + lr->count -= line_len; + return line_len; +} diff --git a/lineread.h b/lineread.h new file mode 100644 index 0000000..b6faff5 --- /dev/null +++ b/lineread.h @@ -0,0 +1,31 @@ +/* SPDX-License-Identifier: AGPL-3.0-or-later + * Copyright Red Hat + * Author: David Gibson <david@gibson.dropbear.id.au> + */ + +#ifndef LINEREAD_H +#define LINEREAD_H + +#define LINEREAD_BUFFER_SIZE 8192 + +/** + * struct lineread - Line reader state + * @fd: File descriptor lines are read from + * @next_line: Offset in @buf of the start of the first line not yet + * returned by lineread_get() + * @count: Number of bytes in @buf read from the file, but not yet + * returned by lineread_get() + * @buf: Buffer storing data read from file. + */ +struct lineread { + int fd; int next_line; + int count; + + /* One extra byte for possible trailing \0 */ + char buf[LINEREAD_BUFFER_SIZE+1]; +}; + +void lineread_init(struct lineread *lr, int fd); +int lineread_get(struct lineread *lr, char **line); + +#endif /* _LINEREAD_H */ |