head fixed (75667a28) · Commits · jan.koester / fresh

commands/text/head.cpp

+50 −0

Changes for commands/text/head.cpp: 50 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		@@ -29,6 +29,11 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		#include <iostream>
		#include <string>
		#include <vector>
		#include <algorithm>
		#include <cstring>
		#include <cerrno>
		#include <unistd.h>
		#include <fcntl.h>

		#include "shell.h"
		#include "textutil.h"
		@@ -95,6 +100,51 @@ namespace fresh { namespace cmd {
		bool first=true;
		for(auto &f: files){
		std::string data;
		if(!allBut){
		// first N lines/bytes: stream and stop early (so
		// "yes \| head" ends), leaving a seekable input
		// positioned right after what was printed
		int fd=f=="-" ? 0 : open(f.c_str(),O_RDONLY);
		if(fd<0){
		out.flush();
		std::cerr << "head: cannot open '" << f << "' for reading: " << strerror(errno) << std::endl;
		status=1;
		continue;
		}
		if(showHeaders){
		out << (first ? "" : "\n") << "==> " << (f=="-" ? "standard input" : f) << " <==\n";
		}
		first=false;
		long long left=count;
		char buf[65536];
		while(left>0){
		ssize_t r=::read(fd,buf,sizeof buf);
		if(r<0){
		if(errno==EINTR) continue;
		out.flush();
		std::cerr << "head: error reading '" << f << "': " << strerror(errno) << std::endl;
		status=1;
		break;
		}
		if(r==0) break;
		size_t take=0;
		if(bytes){
		take=(size_t)std::min<long long>(left,r);
		left-=(long long)take;
		}else{
		while(take<(size_t)r && left>0){
		const char nl=(const char)memchr(buf+take,'\n',(size_t)r-take);
		if(!nl){ take=(size_t)r; break; }
		take=(size_t)(nl-buf)+1;
		--left;
		}
		}
		out.write(buf,take);
		if(take<(size_t)r) lseek(fd,(off_t)take-(off_t)r,SEEK_CUR);
		}
		if(fd!=0) close(fd);
		continue;
		}
		if(!text::readInput(f,data)){
		out.flush();
		std::cerr << "head: cannot open '" << f << "' for reading: " << strerror(errno) << std::endl;