shithub: s3

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cat: support partial downloads

--- a/cat.c

+++ b/cat.c

@@ -7,7 +7,7 @@

 _Noreturn void

 usage(void)

 {

-	fprint(2, "Usage %s: s3://bucket/file\n", argv0);

+	fprint(2, "Usage %s: [-o offset] [-n count] s3://bucket/file\n", argv0);

 	exits("usage");

 }

@@ -15,22 +15,40 @@

 main(int argc , char **argv)

 {

 	S3 s3;

-	int i;

 	Biobuf *b;

 	char path[512];

+	long offset, n;

+	int dorange;

 	tmfmtinstall();

 	fmtinstall('H', encodefmt);

-	i = parseargs(&s3, argc, argv);

-	argc -= i;

-	argv += i;

+	parseargs(&s3, argc, argv);

+	dorange = 0;

+	offset = n = -1;

+	ARGBEGIN{

+	case 'o':

+		dorange++;

+		offset = atoi(EARGF(usage()));

+		break;

+	case 'n':

+		dorange++;

+		n = atoi(EARGF(usage()));

+		break;

+	}ARGEND

 	if(argc == 0)

 		usage();

+	if(dorange && (offset == -1 || n == -1)){

+		fprint(2, "if using ranges both -o and -n must be specified\n");

+		exits("usage");

+	}

 	if(parseuri(&s3, path, sizeof path, argv[0]) < 0)

 		usage();

 	b = Bfdopen(1, OWRITE);

-	download(&s3, path, b, s3get);

+	if(dorange)

+		downloadrange(&s3, path, b, offset, n);

+	else

+		download(&s3, path, b, s3get);

 	Bterm(b);

 	exits(nil);

 }

--- a/cmd.c

+++ b/cmd.c

@@ -3,25 +3,42 @@

 #include <bio.h>

 #include "s3.h"

-void

-download(S3 *s3, char *path, Biobuf *local, int (*fn)(S3*,Hcon*,char*))

+static void

+dump(Hcon *con, Biobuf *out)

 {

 	long n;

-	Hcon con;

 	char data[8192];

-	if(fn(s3, &con, path) < 0)

-		sysfatal("failed to create request: %r");

 	for(;;){

-		n = read(con.body, data, sizeof data);

+		n = read(con->body, data, sizeof data);

 		if(n < 0)

 			sysfatal("download body: %r");

 		if(n == 0){

-			hclose(&con);

+			hclose(con);

 			return;

 		}

-		Bwrite(local, data, n);

+		Bwrite(out, data, n);

 	}

+}

+

+void

+download(S3 *s3, char *path, Biobuf *local, int (*fn)(S3*,Hcon*,char*))

+{

+	Hcon con;

+

+	if(fn(s3, &con, path) < 0)

+		sysfatal("failed to create request: %r");

+	dump(&con, local);

+}

+

+void

+downloadrange(S3 *s3, char *path, Biobuf *local, long off, long n)

+{

+	Hcon con;

+

+	if(s3getrange(s3, &con, path, off, n) < 0)

+		sysfatal("failed to create request: %r");

+	dump(&con, local);

 }

 int

--- a/cmd.h

+++ b/cmd.h

@@ -1,3 +1,4 @@

 void download(S3*, char*, Biobuf*, int (*fn)(S3*,Hcon*,char*));

+void downloadrange(S3*, char*, Biobuf*, long, long);

 int parseuri(S3*, char*, int, char*);

 int parseargs(S3*, int, char**);

--- a/s3.c

+++ b/s3.c

@@ -13,6 +13,7 @@

 	char *method;

 	char time[128];

 	char authhdr[512];

+	char *range;

 } Hreq;

 static void

@@ -59,6 +60,7 @@

 	hreq->path = path;

 	hreq->payhash = payhash;

 	hreq->mime = mime;

+	hreq->range = nil;

 }

 static void

@@ -132,6 +134,8 @@

 		return -1;

 	if(hreq->mime != nil && ctlprint(cfd, "contenttype %s", hreq->mime) < 0)

 		return -1;

+	if(hreq->range != nil && ctlprint(cfd, "headers range: %s", hreq->range) < 0)

+		return -1;

 	return 0;

 }

@@ -223,6 +227,19 @@

 	uchar payhash[SHA2_256dlen];

 	mkreq(&h, "GET", path, payhash, nil);

+	return hopen(con, s3, OREAD, &h);

+}

+

+int

+s3getrange(S3 *s3, Hcon *con, char *path, long off, long n)

+{

+	Hreq h;

+	uchar payhash[SHA2_256dlen];

+	char buf[64];

+

+	mkreq(&h, "GET", path, payhash, nil);

+	snprint(buf, sizeof buf, "bytes=%ld-%ld", off, off+n-1);

+	h.range = buf;

 	return hopen(con, s3, OREAD, &h);

 }

--- a/s3.h

+++ b/s3.h

@@ -20,6 +20,7 @@

 int s3put(S3 *s3, Hcon *con, char *path, char *mime, uchar *payhash);

 int s3post(S3 *s3, Hcon *con, char *path);

 int s3postwrite(S3 *s3, Hcon *con, char *path, char *mime, uchar *payhash);

+int s3getrange(S3 *s3, Hcon *con, char *path, long off, long n);

 void hclose(Hcon *con);

 int hdone(Hcon *con);

-- 

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